Enable SSE for MSVC

Signed-off-by: Jean-Marc Valin <jmvalin@jmvalin.ca>

win32/config.h

@@ -42,6 +42,11 @@ POSSIBILITY OF SUCH DAMAGE.
 #pragma warning(disable : 4996)/* This function or variable may be unsafe. Consider using fopen_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details. */
 #endif
 
+/* Enable SSE functions, if compiled with SSE/SSE2 (note that AMD64 implies SSE2) */
+#if defined(_M_X64) || (defined(_M_IX86_FP) && (_M_IX86_FP >= 1))
+#define __SSE__               1
+#endif
+
 #include "version.h"
 
 #endif /* CONFIG_H */