MIPS: Add big-endian support for MIPS.

src/runtime.cc

Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index 4f340855e907380dc0fa7ceda43a18219fa13227..b6dd3505cb1be12bcf1dc3642c415aae7755524d 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -9184,8 +9184,15 @@ static inline ObjectPair MakePair(MaybeObject* x, MaybeObject* y) {
 #else
 typedef uint64_t ObjectPair;
 static inline ObjectPair MakePair(MaybeObject* x, MaybeObject* y) {
+#if defined(V8_TARGET_LITTLE_ENDIAN)
   return reinterpret_cast<uint32_t>(x) |
       (reinterpret_cast<ObjectPair>(y) << 32);
+#elif defined(V8_TARGET_BIG_ENDIAN)
+    return reinterpret_cast<uint32_t>(y) |
+        (reinterpret_cast<ObjectPair>(x) << 32);
+#else
+#error Unknown endianness
+#endif
 }
 #endif