Fix platforms that don't define UINT64_MAX.

Change-Id: I4b41db30d9c5b280ce20ed4cf2812488c1275395
Reviewed-on: https://boringssl-review.googlesource.com/16785
Reviewed-by: Adam Langley <agl@google.com>

crypto/fipsmodule/cipher/e_aes.c

@@ -68,6 +68,10 @@
 #endif
 
 
+#if !defined(UINT64_MAX)
+#define UINT64_MAX 18446744073709551615ULL
+#endif
+
 OPENSSL_MSVC_PRAGMA(warning(disable: 4702)) /* Unreachable code. */
 
 typedef struct {