AAPT2: Convert binary ResTable_config to proto

Test: make aapt2_tests
Change-Id: I8641f13ce41cd58ac8bc3da31c4e15a7b3f06092
diff --git a/tools/aapt2/ConfigDescription.cpp b/tools/aapt2/ConfigDescription.cpp
index a9278c1..59a6e12 100644
--- a/tools/aapt2/ConfigDescription.cpp
+++ b/tools/aapt2/ConfigDescription.cpp
@@ -876,6 +876,12 @@
   return copy;
 }
 
+std::string ConfigDescription::GetBcp47LanguageTag(bool canonicalize) const {
+  char locale[RESTABLE_MAX_LOCALE_LEN];
+  getBcp47Locale(locale, canonicalize);
+  return std::string(locale);
+}
+
 bool ConfigDescription::Dominates(const ConfigDescription& o) const {
   if (*this == o) {
     return true;