Make sure size_test CI uses -Wall -Werror

Author: mergennachin

test/build_size_test.sh

@@ -15,7 +15,7 @@ cmake_install_executorch_lib() {
   echo "Installing libexecutorch.a"
   clean_executorch_install_folders
 
-  CXXFLAGS="-fno-exceptions -fno-rtti" retry cmake -DBUCK2="$BUCK2" \
+  CXXFLAGS="-fno-exceptions -fno-rtti -Wall -Werror" retry cmake -DBUCK2="$BUCK2" \
           -DCMAKE_CXX_STANDARD_REQUIRED=ON \
           -DCMAKE_INSTALL_PREFIX=cmake-out \
           -DCMAKE_BUILD_TYPE=Release \
@@ -27,7 +27,7 @@ cmake_install_executorch_lib() {
 }
 
 test_cmake_size_test() {
-    CXXFLAGS="-fno-exceptions -fno-rtti" retry cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=cmake-out -Bcmake-out/test test
+    CXXFLAGS="-fno-exceptions -fno-rtti -Wall -Werror" retry cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=cmake-out -Bcmake-out/test test
 
     echo "Build size test"
     cmake --build cmake-out/test -j9 --config Release