Support MIPS64.

MIPS64 confusingly sets __mips__, but it's not a 32-bit platform. This
change updates the defines in base.h to recognise MIPS64 based on both
__mips__ and __LP64__ being defined.

BUG: 19665578

Change-Id: I6290b6def9f999a01b500c918d1488a22fd57460
diff --git a/src/include/openssl/base.h b/src/include/openssl/base.h
index 71223a0..d73f269 100644
--- a/src/include/openssl/base.h
+++ b/src/include/openssl/base.h
@@ -82,9 +82,12 @@
 #elif defined(__aarch64__)
 #define OPENSSL_64_BIT
 #define OPENSSL_AARCH64
-#elif defined(__mips__)
+#elif defined(__mips__) && !defined(__LP64__)
 #define OPENSSL_32_BIT
 #define OPENSSL_MIPS
+#elif defined(__mips__) && defined(__LP64__)
+#define OPENSSL_64_BIT
+#define OPENSSL_MIPS64
 #elif defined(__pnacl__)
 #define OPENSSL_32_BIT
 #define OPENSSL_PNACL