only use -Wno-noexcept-type when it is supported

Summary:
Update CMakeLists.txt to check if the compiler supports `-Wno-noexcept-type`
before adding it to the compiler flags.  This flag is required when building
with gcc 7+, but is unsupported by clang.

Reviewed By: phoad

Differential Revision: D10408987

fbshipit-source-id: 444eeb9f122276c254696fcf5bc99e6b19a393ff

Author: simpkins

CMakeLists.txt

@@ -155,12 +155,18 @@ set(GMOCK_LIBS
 
 set(CMAKE_CXX_STANDARD 14)
 
+include(CheckCXXCompilerFlag)
+
 # Common configuration for all build modes.
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra -pedantic")
-set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-noexcept-type")
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Woverloaded-virtual")
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -g")
 
+CHECK_CXX_COMPILER_FLAG(-Wnoexcept-type COMPILER_HAS_W_NOEXCEPT_TYPE)
+if (COMPILER_HAS_W_NOEXCEPT_TYPE)
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-noexcept-type")
+endif()
+
 set(EXTRA_CXX_FLAGS ${EXTRA_CXX_FLAGS} -Werror)
 
 if("${BUILD_TYPE_LOWER}" MATCHES "debug")