Add backtrace support for mips64.

Change-Id: I12ea2fcbe6780bb596f51988eae1ceafcec858df
diff --git a/debuggerd/utility.h b/debuggerd/utility.h
index 58a882c..49b46e8 100644
--- a/debuggerd/utility.h
+++ b/debuggerd/utility.h
@@ -26,8 +26,10 @@
 #define ABI_STRING "arm"
 #elif defined(__aarch64__)
 #define ABI_STRING "arm64"
-#elif defined(__mips__)
+#elif defined(__mips__) && !defined(__LP64__)
 #define ABI_STRING "mips"
+#elif defined(__mips__) && defined(__LP64__)
+#define ABI_STRING "mips64"
 #elif defined(__i386__)
 #define ABI_STRING "x86"
 #elif defined(__x86_64__)