Fix stack alignment corruption for MinGW32 build

src/platform-win32.cc

Index: src/platform-win32.cc
diff --git a/src/platform-win32.cc b/src/platform-win32.cc
index 191376099ce9b6f3c4c4873a17d076645f68572e..f325cb4143fe73437cb19d2776050734ccb4b35c 100644
--- a/src/platform-win32.cc
+++ b/src/platform-win32.cc
@@ -1479,6 +1479,10 @@ double OS::nan_value() {
 int OS::ActivationFrameAlignment() {
 #ifdef _WIN64
   return 16;  // Windows 64-bit ABI requires the stack to be 16-byte aligned.
+#elif defined(__MINGW32__)
+  // With gcc 4.4 the tree vectorization optimizer can generate code
+  // that requires 16 byte alignment such as movdqa on x86.
+  return 16;
 #else
   return 8;  // Floating-point math runs faster with 8-byte alignment.
 #endif