dsp/lossless: Fix non gcc ARM builds
The workaround for GCC ARM must not be applied when another toolchain
(like MSVC) is used for the build.
@@ -81,7 +81,7 @@ static WEBP_INLINE uint32_t ClampedAddSubtractHalf(uint32_t c0, uint32_t c1,
// gcc <= 4.9 on ARM generates incorrect code in Select() when Sub3() is
// inlined.
-#if defined(__arm__) && LOCAL_GCC_VERSION <= 0x409
+#if defined(__arm__) && defined(__GNUC__) && LOCAL_GCC_VERSION <= 0x409
# define LOCAL_INLINE __attribute__ ((noinline))
#else
# define LOCAL_INLINE WEBP_INLINE
