MIPS: Add rounding support in simulator and RINT instruction.

test/cctest/test-disasm-mips64.cc

Index: test/cctest/test-disasm-mips64.cc
diff --git a/test/cctest/test-disasm-mips64.cc b/test/cctest/test-disasm-mips64.cc
index 2914cb66dda2fc3f57816639f9112df9d863cbb6..5634861e8cb41f23678b01008690fd6c4973af66 100644
--- a/test/cctest/test-disasm-mips64.cc
+++ b/test/cctest/test-disasm-mips64.cc
@@ -685,6 +685,7 @@ TEST(Type1) {
 
     COMPARE(min(D, f3, f4, f5), "462520dc       min.d    f3, f4, f5");
     COMPARE(max(D, f3, f4, f5), "462520de       max.d    f3, f4, f5");
+    COMPARE(rint_d(f8, f6), "4620321a       rint.d    f8, f6");
     VERIFY_RUN();
   }
 }