Add library "Utility" folder in include paths together with library

I don't know the reason why it was not placed here already, the git log
doesn't give much hints. Anyway this change prepares for the next commit
where the Library field is being removed from SourceFile struct.

Author: cmaglie

legacy/builder/container_find_includes.go

@@ -332,9 +332,6 @@ func (f *CppIncludesFinder) findIncludesUntilDone(sourceFile SourceFile) error {
 		f.cache.ExpectFile(sourcePath)
 
 		includes := f.ctx.IncludeFolders
-		if sourceFile.Library != nil && sourceFile.Library.UtilityDir != nil {
-			includes = append(includes, sourceFile.Library.UtilityDir)
-		}
 		var preproc_err error
 		var preproc_stderr []byte
 		if unchanged && f.cache.valid {
@@ -393,6 +390,10 @@ func (f *CppIncludesFinder) findIncludesUntilDone(sourceFile SourceFile) error {
 		// include scanning
 		f.ctx.ImportedLibraries = append(f.ctx.ImportedLibraries, library)
 		f.appendIncludeFolder(sourcePath, include, library.SourceDir)
+		if library.UtilityDir != nil {
+			// TODO: Use library.SourceDirs() instead?
+			includes = append(includes, library.UtilityDir)
+		}
 		sourceDirs := library.SourceDirs()
 		for _, sourceDir := range sourceDirs {
 			f.queueSourceFilesFromFolder(library, sourceDir.Dir, sourceDir.Recurse)