s390: using uintptr to fix gcc error

Wsign-compare was recently added which exposed this
issue. Using the correct type fixes the error.

R=joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com
BUG=
LOG=N

Review-Url: https://codereview.chromium.org/2528433003
Cr-Commit-Position: refs/heads/master@{#41196}

src/s390/simulator-s390.cc

@@ -5682,7 +5682,7 @@ void Simulator::CallInternal(byte* entry, int reg_arg_count) {
 
   // Set up the non-volatile registers with a known value. To be able to check
   // that they are preserved properly across JS execution.
-  intptr_t callee_saved_value = icount_;
+  uintptr_t callee_saved_value = icount_;
   if (reg_arg_count < 5) {
     set_register(r6, callee_saved_value + 6);
   }
@@ -5762,7 +5762,7 @@ intptr_t Simulator::Call(byte* entry, int argument_count, ...) {
   // Remaining arguments passed on stack.
   int64_t original_stack = get_register(sp);
   // Compute position of stack on entry to generated code.
-  intptr_t entry_stack =
+  uintptr_t entry_stack =
       (original_stack -
        (kCalleeRegisterSaveAreaSize + stack_arg_count * sizeof(intptr_t)));
   if (base::OS::ActivationFrameAlignment() != 0) {
@@ -5798,7 +5798,7 @@ intptr_t Simulator::Call(byte* entry, int argument_count, ...) {
 
   // Set up the non-volatile registers with a known value. To be able to check
   // that they are preserved properly across JS execution.
-  intptr_t callee_saved_value = icount_;
+  uintptr_t callee_saved_value = icount_;
   if (reg_arg_count < 5) {
     set_register(r6, callee_saved_value + 6);
   }