Add _M_IX86 for testing for MSVC x86
diff --git a/tommath_private.h b/tommath_private.h
index 0c94831..624ba0a 100644
--- a/tommath_private.h
+++ b/tommath_private.h
@@ -166,7 +166,7 @@ MP_STATIC_ASSERT(prec_geq_min_prec, MP_DEFAULT_DIGIT_COUNT >= MP_MIN_DIGIT_COUNT
#if defined(__STDC_IEC_559__) || defined(__GCC_IEC_559) \
|| defined(__x86_64__) || defined(_M_X64) || defined(_M_AMD64) \
- || defined(__i386__) || defined(_M_X86) \
+ || defined(__i386__) || defined(_M_X86) || defined(_M_IX86) \
|| defined(__aarch64__) || defined(__arm__)
#define MP_HAS_SET_DOUBLE
#endif