Add `cxx_strict_flags` for clang to match FreeBSD's WARNS flags

Signed-off-by: Enji Cooper <yaneurabeya@gmail.com>

googletest/cmake/internal_utils.cmake

@@ -81,6 +81,7 @@ macro(config_compiler_and_linker)
     set(cxx_base_flags "-Wall -Wshadow -Werror")
     set(cxx_exception_flags "-fexceptions")
     set(cxx_no_exception_flags "-fno-exceptions")
+    set(cxx_strict_flags "-Wno-format-y2k -W -Wpointer-arith -Wreturn-type -Wcast-qual -Wwrite-strings -Wswitch -Wunused-parameter -Wcast-align -Wchar-subscripts -Winline -Wredundant-decls")
   elseif (CMAKE_COMPILER_IS_GNUCXX)
     set(cxx_base_flags "-Wall -Wshadow -Werror")
     if(NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 7.0.0)