Revert D6155682: Use clang-5.0 -Oz

Differential Revision: D6155682

fbshipit-source-id: 9139ed14e0d24784bf25b2783e364a511173ab83

ReactCommon/yoga/yoga/Yoga.cpp

@@ -133,12 +133,6 @@ static int YGDefaultLog(const YGConfigRef config,
 #endif
 
 bool YGFloatIsUndefined(const float value) {
-// TODO(gkm): Ugh! Some Android builds (r13b & clang-3.8) fail
-// with the kludge below, so we must tailor it specifically for
-// NDK r15c which has clang-5.0. NDK r16 will make it all better.
-#if __ANDROID__ && __clang_major__ == 5 // TODO(gkm): remove for NDK >= 16
-  using std::isnan;
-#endif
   return isnan(value);
 }