Add target/os configurable string_list attrs.

Starting with copts for cc_object, with an extracted function that can
be shared with other cc_* module types.

Test: TH
Change-Id: I9025232e83a3dcd0ca243387486fafbdbd3e2d9b
diff --git a/cc/library_headers.go b/cc/library_headers.go
index c8dd2c2..82af16a 100644
--- a/cc/library_headers.go
+++ b/cc/library_headers.go
@@ -62,6 +62,7 @@
 }
 
 type bazelCcLibraryHeadersAttributes struct {
+	Copts    bazel.StringListAttribute
 	Hdrs     bazel.LabelListAttribute
 	Includes bazel.LabelListAttribute
 	Deps     bazel.LabelListAttribute
@@ -99,6 +100,7 @@
 	headerLibsLabels := bp2BuildParseHeaderLibs(ctx, module)
 
 	attrs := &bazelCcLibraryHeadersAttributes{
+		Copts:    bp2BuildParseCflags(ctx, module),
 		Includes: exportedIncludesLabels,
 		Hdrs:     exportedIncludesHeadersLabels,
 		Deps:     headerLibsLabels,