Add diff_flags as a header_abi_checker property

The property allows developers to add extra flags to header-abi-diff for
specific libraries.

Bug: 232891473
Test: m libbinder.vendor
Change-Id: I203af73c784dfc7738bb64f57b224c08d5c595ce
Merged-In: I203af73c784dfc7738bb64f57b224c08d5c595ce
(cherry picked from commit 4f992b663fdb0f422a772ba2df9ef8ca9b6a7d6e)
diff --git a/cc/builder.go b/cc/builder.go
index 107cd58..468452d 100644
--- a/cc/builder.go
+++ b/cc/builder.go
@@ -957,9 +957,10 @@
 	return outputFile
 }
 
-// sourceAbiDiff registers a build statement to compare linked sAbi dump files (.ldump).
+// sourceAbiDiff registers a build statement to compare linked sAbi dump files (.lsdump).
 func sourceAbiDiff(ctx android.ModuleContext, inputDump android.Path, referenceDump android.Path,
-	baseName, exportedHeaderFlags string, checkAllApis, isLlndk, isNdk, isVndkExt bool) android.OptionalPath {
+	baseName, exportedHeaderFlags string, diffFlags []string,
+	checkAllApis, isLlndk, isNdk, isVndkExt bool) android.OptionalPath {
 
 	outputFile := android.PathForModuleOut(ctx, baseName+".abidiff")
 	libName := strings.TrimSuffix(baseName, filepath.Ext(baseName))
@@ -990,6 +991,8 @@
 	if isVndkExt {
 		extraFlags = append(extraFlags, "-allow-extensions")
 	}
+	// TODO(b/232891473): Simplify the above logic with diffFlags.
+	extraFlags = append(extraFlags, diffFlags...)
 
 	ctx.Build(pctx, android.BuildParams{
 		Rule:        sAbiDiff,
diff --git a/cc/library.go b/cc/library.go
index d819c62..36756ec 100644
--- a/cc/library.go
+++ b/cc/library.go
@@ -110,6 +110,9 @@
 		// Run checks on all APIs (in addition to the ones referred by
 		// one of exported ELF symbols.)
 		Check_all_apis *bool
+
+		// Extra flags passed to header-abi-diff
+		Diff_flags []string
 	}
 
 	// Inject boringssl hash into the shared library.  This is only intended for use by external/boringssl.
@@ -1634,6 +1637,7 @@
 		if refAbiDumpFile != nil {
 			library.sAbiDiff = sourceAbiDiff(ctx, library.sAbiOutputFile.Path(),
 				refAbiDumpFile, fileName, exportedHeaderFlags,
+				library.Properties.Header_abi_checker.Diff_flags,
 				Bool(library.Properties.Header_abi_checker.Check_all_apis),
 				ctx.IsLlndk(), ctx.isNdk(ctx.Config()), ctx.IsVndkExt())
 		}