For abi diffing, factor in arch variant and primary arch.

binder_size_t has a different size for builds with different primary
arches.

Also maintain seperate reference dumps for different arch variants,
since different cflags may be legally specified for them (similar to
what GSI does)

Test: create reference dump for libjpeg at
      prebuilts/abi-dumps/vndk/current/arm64/arm64_armv8-a/source-based/libjpeg.so.lsdump.gz
      mm -j64; header-abi-diff gets invoked.

Change-Id: I55eae4d4811c9754fe8dbd1009c7929fea119eeb

android/paths.go

@@ -776,7 +776,12 @@ func pathForModule(ctx ModuleContext) OutputPath {
 // PathForVndkRefDump returns an OptionalPath representing the path of the reference
 // abi dump for the given module. This is not guaranteed to be valid.
 func PathForVndkRefAbiDump(ctx ModuleContext, version, fileName string, vndkOrNdk, isSourceDump bool) OptionalPath {
-	archName := ctx.Arch().ArchType.Name
+	arches := ctx.DeviceConfig().Arches()
+	currentArch := ctx.Arch()
+	archNameAndVariant := currentArch.ArchType.String()
+	if currentArch.ArchVariant != "" {
+		archNameAndVariant += "_" + currentArch.ArchVariant
+	}
 	var sourceOrBinaryDir string
 	var vndkOrNdkDir string
 	var ext string
@@ -792,8 +797,12 @@ func PathForVndkRefAbiDump(ctx ModuleContext, version, fileName string, vndkOrNd
 	} else {
 		vndkOrNdkDir = "ndk"
 	}
-	refDumpFileStr := "prebuilts/abi-dumps/" + vndkOrNdkDir + "/" + version + "/" +
-		archName + "/" + sourceOrBinaryDir + "/" + fileName + ext
+	if len(arches) == 0 {
+		panic("device build with no primary arch")
+	}
+	primary_arch := arches[0].ArchType.String()
+	refDumpFileStr := "prebuilts/abi-dumps/" + vndkOrNdkDir + "/" + version + "/" + primary_arch + "/" +
+		archNameAndVariant + "/" + sourceOrBinaryDir + "/" + fileName + ext
 	return ExistentPathForSource(ctx, refDumpFileStr)
 }