Pass --remap-path-prefix to Rust builds.

We need to pass --remap-path-prefix to Rust builds to ensure that they
are reproducible across different paths.  This adds that for both host
and device builds.

Test: Verify host and device builds are reproducible with different
directories.

Change-Id: I68ba31537b2332fd05613aa0fb00a1502d78e410

rust/compiler.go

@@ -120,6 +120,7 @@ func (compiler *baseCompiler) compilerFlags(ctx ModuleContext, flags Flags) Flag
 	flags.RustFlags = append(flags.RustFlags, compiler.featuresToFlags(compiler.Properties.Features)...)
 	flags.RustFlags = append(flags.RustFlags, "--edition="+*compiler.Properties.Edition)
 	flags.LinkFlags = append(flags.LinkFlags, compiler.Properties.Ld_flags...)
+	flags.GlobalRustFlags = append(flags.GlobalRustFlags, config.GlobalRustFlags...)
 	flags.GlobalRustFlags = append(flags.GlobalRustFlags, ctx.toolchain().ToolchainRustFlags())
 	flags.GlobalLinkFlags = append(flags.GlobalLinkFlags, ctx.toolchain().ToolchainLinkFlags())
 

rust/config/global.go

@@ -37,6 +37,10 @@ var (
 
 	DefaultDenyWarnings = proptools.BoolPtr(true)
 
+	GlobalRustFlags = []string{
+		"--remap-path-prefix $$(pwd)=",
+	}
+
 	deviceGlobalRustFlags = []string{}
 
 	deviceGlobalLinkFlags = []string{