[mypyc] librt base64: check for SSE before enabling the rest, to fix macOS universal builds

Author: mr-c

mypyc/lib-rt/base64/config.h

@@ -1,7 +1,7 @@
 #ifndef BASE64_CONFIG_H
 #define BASE64_CONFIG_H
 
-#if (defined(__x86_64__) && defined(__LP64__)) || defined(_M_X64)
+#if defined(__SSE__) && ((defined(__x86_64__) && defined(__LP64__)) || defined(_M_X64))
   #define HAVE_SSSE3 1
   #define HAVE_SSE41 1
   #define HAVE_SSE42 1