Expose real GccVersion

In order to validate that the NDK STL paths exists, we need to know
the full path, including the Gcc version during the go execution. So
instead of returning a ninja variable reference, just return the
contents of the variable.

This also fixes a few invalid uses of armGccVersion to the proper
variable.

Change-Id: I54398ba4aa4000235b7d537a2c4efe3ecbbeec8b

cc/arm64_device.go

@@ -71,8 +71,12 @@ var (
 	}
 )
 
+const (
+	arm64GccVersion = "4.9"
+)
+
 func init() {
-	pctx.StaticVariable("arm64GccVersion", "4.9")
+	pctx.StaticVariable("arm64GccVersion", arm64GccVersion)
 
 	pctx.StaticVariable("arm64GccRoot",
 		"prebuilts/gcc/${HostPrebuiltTag}/aarch64/aarch64-linux-android-${arm64GccVersion}")
@@ -115,7 +119,7 @@ func (t *toolchainArm64) GccTriple() string {
 }
 
 func (t *toolchainArm64) GccVersion() string {
-	return "${arm64GccVersion}"
+	return arm64GccVersion
 }
 
 func (t *toolchainArm64) Cflags() string {

cc/arm_device.go

@@ -121,6 +121,10 @@ var (
 	armClangArchVariantCflags = copyVariantFlags(armArchVariantCflags)
 )
 
+const (
+	armGccVersion = "4.9"
+)
+
 func copyVariantFlags(m map[string][]string) map[string][]string {
 	ret := make(map[string][]string, len(m))
 	for k, v := range m {
@@ -148,7 +152,7 @@ func init() {
 		"-mfpu=neon-vfpv4",
 	}
 
-	pctx.StaticVariable("armGccVersion", "4.9")
+	pctx.StaticVariable("armGccVersion", armGccVersion)
 
 	pctx.StaticVariable("armGccRoot",
 		"prebuilts/gcc/${HostPrebuiltTag}/arm/arm-linux-androideabi-${armGccVersion}")
@@ -268,7 +272,7 @@ func (t *toolchainArm) GccTriple() string {
 }
 
 func (t *toolchainArm) GccVersion() string {
-	return "${armGccVersion}"
+	return armGccVersion
 }
 
 func (t *toolchainArm) ToolchainCflags() string {

cc/mips64_device.go

@@ -80,14 +80,18 @@ var (
 	}
 )
 
+const (
+	mips64GccVersion = "4.9"
+)
+
 func init() {
 	common.RegisterArchFeatures(common.Mips64, "mips64r6",
 		"rev6")
 
-	pctx.StaticVariable("mips64GccVersion", "4.9")
+	pctx.StaticVariable("mips64GccVersion", mips64GccVersion)
 
 	pctx.StaticVariable("mips64GccRoot",
-		"prebuilts/gcc/${HostPrebuiltTag}/mips/mips64el-linux-android-${armGccVersion}")
+		"prebuilts/gcc/${HostPrebuiltTag}/mips/mips64el-linux-android-${mips64GccVersion}")
 
 	pctx.StaticVariable("mips64GccTriple", "mips64el-linux-android")
 
@@ -138,7 +142,7 @@ func (t *toolchainMips64) GccTriple() string {
 }
 
 func (t *toolchainMips64) GccVersion() string {
-	return "${mips64GccVersion}"
+	return mips64GccVersion
 }
 
 func (t *toolchainMips64) ToolchainLdflags() string {

cc/mips_device.go

@@ -111,14 +111,18 @@ var (
 	}
 )
 
+const (
+	mipsGccVersion = "4.9"
+)
+
 func init() {
 	common.RegisterArchFeatures(common.Mips, "mips32r6",
 		"rev6")
 
-	pctx.StaticVariable("mipsGccVersion", "4.9")
+	pctx.StaticVariable("mipsGccVersion", mipsGccVersion)
 
 	pctx.StaticVariable("mipsGccRoot",
-		"prebuilts/gcc/${HostPrebuiltTag}/mips/mips64el-linux-android-${armGccVersion}")
+		"prebuilts/gcc/${HostPrebuiltTag}/mips/mips64el-linux-android-${mipsGccVersion}")
 
 	pctx.StaticVariable("mipsGccTriple", "mips64el-linux-android")
 
@@ -170,7 +174,7 @@ func (t *toolchainMips) GccTriple() string {
 }
 
 func (t *toolchainMips) GccVersion() string {
-	return "${mipsGccVersion}"
+	return mipsGccVersion
 }
 
 func (t *toolchainMips) ToolchainLdflags() string {

cc/toolchain.go

@@ -46,7 +46,9 @@ type Toolchain interface {
 
 	GccRoot() string
 	GccTriple() string
+	// GccVersion should return a real value, not a ninja reference
 	GccVersion() string
+
 	ToolchainCflags() string
 	ToolchainLdflags() string
 	Cflags() string

cc/x86_64_device.go

@@ -92,6 +92,10 @@ var (
 	}
 )
 
+const (
+	x86_64GccVersion = "4.9"
+)
+
 func init() {
 	common.RegisterArchFeatures(common.X86_64, "",
 		"ssse3",
@@ -131,10 +135,10 @@ func init() {
 		"aes_ni",
 		"popcnt")
 
-	pctx.StaticVariable("x86_64GccVersion", "4.9")
+	pctx.StaticVariable("x86_64GccVersion", x86_64GccVersion)
 
 	pctx.StaticVariable("x86_64GccRoot",
-		"prebuilts/gcc/${HostPrebuiltTag}/x86/x86_64-linux-android-${armGccVersion}")
+		"prebuilts/gcc/${HostPrebuiltTag}/x86/x86_64-linux-android-${x86_64GccVersion}")
 
 	pctx.StaticVariable("x86_64GccTriple", "x86_64-linux-android")
 
@@ -186,7 +190,7 @@ func (t *toolchainX86_64) GccTriple() string {
 }
 
 func (t *toolchainX86_64) GccVersion() string {
-	return "${x86_64GccVersion}"
+	return x86_64GccVersion
 }
 
 func (t *toolchainX86_64) ToolchainLdflags() string {

cc/x86_darwin_host.go

@@ -74,11 +74,15 @@ var (
 	darwinClangCppflags = clangFilterUnknownCflags(darwinCppflags)
 )
 
+const (
+	darwinGccVersion = "4.2.1"
+)
+
 func init() {
 	pctx.StaticVariable("macSdkPath", "/Applications/Xcode.app/Contents/Developer")
 	pctx.StaticVariable("macSdkRoot", "${macSdkPath}/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk")
 
-	pctx.StaticVariable("darwinGccVersion", "4.2.1")
+	pctx.StaticVariable("darwinGccVersion", darwinGccVersion)
 	pctx.StaticVariable("darwinGccRoot",
 		"${SrcDir}/prebuilts/gcc/${HostPrebuiltTag}/host/i686-apple-darwin-${darwinGccVersion}")
 
@@ -137,7 +141,7 @@ func (t *toolchainDarwin) GccTriple() string {
 }
 
 func (t *toolchainDarwin) GccVersion() string {
-	return "${darwinGccVersion}"
+	return darwinGccVersion
 }
 
 func (t *toolchainDarwin) Cflags() string {

cc/x86_device.go

@@ -95,6 +95,10 @@ var (
 	}
 )
 
+const (
+	x86GccVersion = "4.9"
+)
+
 func init() {
 	common.RegisterArchFeatures(common.X86, "atom",
 		"ssse3",
@@ -133,10 +137,10 @@ func init() {
 		"popcnt",
 		"movbe")
 
-	pctx.StaticVariable("x86GccVersion", "4.9")
+	pctx.StaticVariable("x86GccVersion", x86GccVersion)
 
 	pctx.StaticVariable("x86GccRoot",
-		"prebuilts/gcc/${HostPrebuiltTag}/x86/x86_64-linux-android-${armGccVersion}")
+		"prebuilts/gcc/${HostPrebuiltTag}/x86/x86_64-linux-android-${x86GccVersion}")
 
 	pctx.StaticVariable("x86GccTriple", "x86_64-linux-android")
 
@@ -188,7 +192,7 @@ func (t *toolchainX86) GccTriple() string {
 }
 
 func (t *toolchainX86) GccVersion() string {
-	return "${x86GccVersion}"
+	return x86GccVersion
 }
 
 func (t *toolchainX86) ToolchainLdflags() string {

cc/x86_linux_host.go

@@ -101,8 +101,12 @@ var (
 	}
 )
 
+const (
+	linuxGccVersion = "4.8"
+)
+
 func init() {
-	pctx.StaticVariable("linuxGccVersion", "4.8")
+	pctx.StaticVariable("linuxGccVersion", linuxGccVersion)
 
 	pctx.StaticVariable("linuxGccRoot",
 		"${SrcDir}/prebuilts/gcc/${HostPrebuiltTag}/host/x86_64-linux-glibc2.15-${linuxGccVersion}")
@@ -163,7 +167,7 @@ func (t *toolchainLinux) GccTriple() string {
 }
 
 func (t *toolchainLinux) GccVersion() string {
-	return "${linuxGccVersion}"
+	return linuxGccVersion
 }
 
 func (t *toolchainLinuxX86) Cflags() string {

cc/x86_windows_host.go

@@ -61,8 +61,12 @@ var (
 	}
 )
 
+const (
+	windowsGccVersion = "4.8"
+)
+
 func init() {
-	pctx.StaticVariable("windowsGccVersion", "4.8")
+	pctx.StaticVariable("windowsGccVersion", windowsGccVersion)
 
 	pctx.StaticVariable("windowsGccRoot",
 		"${SrcDir}/prebuilts/gcc/${HostPrebuiltTag}/host/x86_64-w64-mingw32-${windowsGccVersion}")
@@ -92,7 +96,7 @@ func (t *toolchainWindows) GccTriple() string {
 }
 
 func (t *toolchainWindows) GccVersion() string {
-	return "${windowsGccVersion}"
+	return windowsGccVersion
 }
 
 func (t *toolchainWindows) Cflags() string {