only append -fimplicit-templates if -fno-implicit-templates is already there...

only append -fimplicit-templates if -fno-implicit-templates is already there because of mysql/mariadb

cmake_modules/TokuSetupCompiler.cmake

@@ -92,15 +92,16 @@ set_cflags_if_supported(
   )
 ## set_cflags_if_supported_named("-Weffc++" -Weffcpp)
 
-## Clang has stricter POD checks.  So, only enable this warning on our other builds (Linux + GCC)
-if (NOT CMAKE_CXX_COMPILER_ID MATCHES Clang)
+if (CMAKE_CXX_FLAGS MATCHES -fno-implicit-templates)
   # must append this because mysql sets -fno-implicit-templates and we need to override it
-  # also clang doesn't support it on osx but also doesn't seem to know that
   check_cxx_compiler_flag(-fimplicit-templates HAVE_CXX_-fimplicit-templates)
   if (HAVE_CXX_-fimplicit-templates)
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fimplicit-templates")
   endif ()
+endif()
 
+## Clang has stricter POD checks.  So, only enable this warning on our other builds (Linux + GCC)
+if (NOT CMAKE_CXX_COMPILER_ID MATCHES Clang)
   set_cflags_if_supported(
     -Wpacked
     )