Support arch variations for export_system_include_dirs in cc_library_headers bp2build converter.

Test: Added unit test
Test: bp2build-sync.py write; bazel build //bionic/... works for more cc_library_static targets (in a parent CL)
Change-Id: Ib487216a4bcbc52958ff948722dae347b0d8b606
diff --git a/cc/library_headers.go b/cc/library_headers.go
index 82af16a..d35748b 100644
--- a/cc/library_headers.go
+++ b/cc/library_headers.go
@@ -64,7 +64,7 @@
 type bazelCcLibraryHeadersAttributes struct {
 	Copts    bazel.StringListAttribute
 	Hdrs     bazel.LabelListAttribute
-	Includes bazel.LabelListAttribute
+	Includes bazel.StringListAttribute
 	Deps     bazel.LabelListAttribute
 }
 
@@ -95,15 +95,15 @@
 		return
 	}
 
-	exportedIncludesLabels, exportedIncludesHeadersLabels := bp2BuildParseExportedIncludes(ctx, module)
+	exportedIncludes, exportedIncludesHeaders := bp2BuildParseExportedIncludes(ctx, module)
 
-	headerLibsLabels := bp2BuildParseHeaderLibs(ctx, module)
+	headerLibs := bp2BuildParseHeaderLibs(ctx, module)
 
 	attrs := &bazelCcLibraryHeadersAttributes{
 		Copts:    bp2BuildParseCflags(ctx, module),
-		Includes: exportedIncludesLabels,
-		Hdrs:     exportedIncludesHeadersLabels,
-		Deps:     headerLibsLabels,
+		Includes: exportedIncludes,
+		Hdrs:     exportedIncludesHeaders,
+		Deps:     headerLibs,
 	}
 
 	props := bazel.BazelTargetModuleProperties{