AAPT2: Support -c configuration filtering

Change-Id: I1e5855ca73440bdc30c21bcbc1dfdd31a9842363
diff --git a/tools/aapt2/Locale.cpp b/tools/aapt2/Locale.cpp
index 0369156..6acf3b0 100644
--- a/tools/aapt2/Locale.cpp
+++ b/tools/aapt2/Locale.cpp
@@ -70,7 +70,7 @@
     return std::all_of(std::begin(str), std::end(str), ::isdigit);
 }
 
-bool LocaleValue::initFromFilterString(const std::string& str) {
+bool LocaleValue::initFromFilterString(const StringPiece& str) {
      // A locale (as specified in the filter) is an underscore separated name such
      // as "en_US", "en_Latn_US", or "en_US_POSIX".
      std::vector<std::string> parts = util::splitAndLowercase(str, '_');