Fix double-rounding in strtod for MinGW

src/strtod.cc

Index: src/strtod.cc
===================================================================
--- src/strtod.cc	(revision 10915)
+++ src/strtod.cc	(working copy)
@@ -175,11 +175,12 @@
 static bool DoubleStrtod(Vector<const char> trimmed,
                          int exponent,
                          double* result) {
-#if (defined(V8_TARGET_ARCH_IA32) || defined(USE_SIMULATOR)) && !defined(WIN32)
+#if (defined(V8_TARGET_ARCH_IA32) || defined(USE_SIMULATOR)) \
+    && !defined(_MSC_VER)
   // On x86 the floating-point stack can be 64 or 80 bits wide. If it is
   // 80 bits wide (as is the case on Linux) then double-rounding occurs and the
   // result is not accurate.
-  // We know that Windows32 uses 64 bits and is therefore accurate.
+  // We know that Windows32 with MSVC uses 64 bits and is therefore accurate.
   // Note that the ARM simulator is compiled for 32bits. It therefore exhibits
   // the same problem.
   return false;