trying both c++11 and c++14 narrowing

Author: miladm

build_torch_xla_libs.sh

@@ -57,6 +57,7 @@ fi
 OPTS+=(--cxxopt="-std=c++17")
 if [[ $(basename -- $CC) =~ ^clang ]]; then
   OPTS+=(--cxxopt="-Wno-c++11-narrowing")
+  OPTS+=(--cxxopt="-Wno-c++14-narrowing")
 fi
 
 if [[ "$XLA_CUDA" == "1" ]]; then