Incorporate cc_library_headers into mixed builds

Test: go soong tests
Test: bp2build generate & sync; mixed build libc; mixed build su (su is
      an Android.mk target that relies on converted a cc_library_headers)
Bug: 181552740
Change-Id: I9efd587970551fd41f642a208f0aa0a80e8694e0

cc/library_sdk_member.go

@@ -162,9 +162,16 @@ func (mt *librarySdkMemberType) CreateVariantPropertiesStruct() android.SdkMembe
 	return &nativeLibInfoProperties{memberType: mt}
 }
 
+func isBazelOutDirectory(p android.Path) bool {
+	_, bazel := p.(android.BazelOutPath)
+	return bazel
+}
+
 func isGeneratedHeaderDirectory(p android.Path) bool {
 	_, gen := p.(android.WritablePath)
-	return gen
+	// TODO(b/183213331): Here we assume that bazel-based headers are not generated; we need
+	// to support generated headers in mixed builds.
+	return gen && !isBazelOutDirectory(p)
 }
 
 type includeDirsProperty struct {