Merge pull request #338 from Gravecat/mingw-fix

Fixes compilation on GCC/MinGW

Author: lemire

include/fast_float/float_common.h

@@ -406,8 +406,8 @@ full_multiplication(uint64_t a, uint64_t b) {
   // But MinGW on ARM64 doesn't have native support for 64-bit multiplications
   answer.high = __umulh(a, b);
   answer.low = a * b;
-#elif defined(FASTFLOAT_32BIT) ||                                              \
-    (defined(_WIN64) && !defined(__clang__) && !defined(_M_ARM64))
+#elif defined(FASTFLOAT_32BIT) || (defined(_WIN64) && !defined(__clang__) &&   \
+                                   !defined(_M_ARM64) && !defined(__GNUC__))
   answer.low = _umul128(a, b, &answer.high); // _umul128 not available on ARM64
 #elif defined(FASTFLOAT_64BIT) && defined(__SIZEOF_INT128__)
   __uint128_t r = ((__uint128_t)a) * b;