MIPS64: Fix bugs in branches for unsigned conditions.

src/mips64/simulator-mips64.cc

Index: src/mips64/simulator-mips64.cc
diff --git a/src/mips64/simulator-mips64.cc b/src/mips64/simulator-mips64.cc
index 5ddad8d5b4651214b96f69e1dbf435cdefea0a80..bea3bad7a02d8fed3bf4c8698cc140d9c42ffa9a 100644
--- a/src/mips64/simulator-mips64.cc
+++ b/src/mips64/simulator-mips64.cc
@@ -2973,7 +2973,7 @@ void Simulator::DecodeTypeImmediate(Instruction* instr) {
       alu_out = (rs < se_imm16) ? 1 : 0;
       break;
     case SLTIU:
-      alu_out = (rs_u < static_cast<uint32_t>(se_imm16)) ? 1 : 0;
+      alu_out = (rs_u < static_cast<uint64_t>(se_imm16)) ? 1 : 0;
       break;
     case ANDI:
         alu_out = rs & oe_imm16;