Check for MSVC before setting MSVC-style flag

Author: anthony-linaro

share/cmake/utils/CompilerFlags.cmake

@@ -19,7 +19,7 @@ if(OCIO_USE_SIMD)
     if (OCIO_USE_SSE2NEON AND COMPILER_SUPPORTS_ARM_NEON)
         include(CheckSupportSSEUsingSSE2NEON)
         if(COMPILER_SUPPORTS_SSE_WITH_SSE2NEON)
-            if(WIN32)
+            if(WIN32 AND MSVC)
                 # Enable the "new" preprocessor, to more closely match Clang/GCC, required for sse2neon
                 set(PLATFORM_COMPILE_OPTIONS "${PLATFORM_COMPILE_OPTIONS};/Zc:preprocessor")
             endif()