X87: Change the test case for X87 RunRoundInt32ToFloat32.

 The CL #33347 (https://codereview.chromium.org/1589363002) added the RunRoundInt32ToFloat32 test case and X87 failed at it.

 The reason is same as the CL #31808 (issue 1430943002, X87: Change the test case for X87 float operations), please refer: https://codereview.chromium.org/1430943002/.

 Here is the key comments from CL #31808
 Some new test cases use CheckFloatEq(...) and CheckDoubleEq(...) function for result check. When GCC compiling the CheckFloatEq() and CheckDoubleEq() function,
 those inlined functions has different behavior comparing with GCC ia32 build and x87 build.
 The major difference is sse float register still has single precision rounding semantic. While X87 register has no such rounding precsion semantic when directly use register value.
 The V8 turbofan JITTed has exactly same result in both X87 and IA32 port.

 For CHECK_EQ(a, b) function, if a and b are doubles, it will has similar behaviors like CheckFloatEq(...) and CheckDoubleEq(...) function when compiled by GCC and causes the test case
 fail.

 So we add the following sentence to do type case to keep the same precision for RunRoundInt32ToFloat32. Such as: volatile double expect = static_cast<float>(*i).

BUG=

Review URL: https://codereview.chromium.org/1649323002

Cr-Commit-Position: refs/heads/master@{#33630}

test/cctest/compiler/test-run-machops.cc

@@ -6015,7 +6015,10 @@ TEST(RunBitcastFloat32ToInt32) {
 TEST(RunRoundInt32ToFloat32) {
   BufferedRawMachineAssemblerTester<float> m(MachineType::Int32());
   m.Return(m.RoundInt32ToFloat32(m.Parameter(0)));
-  FOR_INT32_INPUTS(i) { CHECK_EQ(static_cast<float>(*i), m.Call(*i)); }
+  FOR_INT32_INPUTS(i) {
+    volatile float expected = static_cast<float>(*i);
+    CHECK_EQ(expected, m.Call(*i));
+  }
 }