Add mips64 port.

src/objects.cc

Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index f4522db01d9e2fadba75d3e0dc9c4ffe315e1877..fccf97a68a97c8cd8a2bba834bd4f6d5a88e72bc 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -9012,8 +9012,8 @@ static inline bool CompareRawStringContents(const Char* const a,
   // then we have to check that the strings are aligned before
   // comparing them blockwise.
   const int kAlignmentMask = sizeof(uint32_t) - 1;  // NOLINT
-  uint32_t pa_addr = reinterpret_cast<uint32_t>(a);
-  uint32_t pb_addr = reinterpret_cast<uint32_t>(b);
+  uintptr_t pa_addr = reinterpret_cast<uintptr_t>(a);
+  uintptr_t pb_addr = reinterpret_cast<uintptr_t>(b);
   if (((pa_addr & kAlignmentMask) | (pb_addr & kAlignmentMask)) == 0) {
 #endif
     const int kStepSize = sizeof(int) / sizeof(Char);  // NOLINT