Remove library decorator for extracting headers

It is unused and removing it allows us to use the same function for
prebuilt/not libraries.

Test: bp2build.sh
Change-Id: I92ac56496cff2c2e55d6eb9f261fe75a1b232856
diff --git a/cc/library_headers.go b/cc/library_headers.go
index 41ebcc7..cdeb392 100644
--- a/cc/library_headers.go
+++ b/cc/library_headers.go
@@ -122,7 +122,7 @@
 
 func libraryHeadersBp2Build(ctx android.TopDownMutatorContext, module *Module) {
 	baseAttributes := bp2BuildParseBaseProps(ctx, module)
-	exportedIncludes := bp2BuildParseExportedIncludes(ctx, module, baseAttributes.includes)
+	exportedIncludes := bp2BuildParseExportedIncludes(ctx, module, &baseAttributes.includes)
 	linkerAttrs := baseAttributes.linkerAttributes
 
 	attrs := &bazelCcLibraryHeadersAttributes{