Remove extraneous line from CompareWrapper test

On platforms without TurboFan (PowerPC) the CompareWrapper test was
failing. It appears the line

RawMachineAssemblerTester<int32_t> m;

was causing the issue, and does not appear to be required for the
test to operate correctly. Removing it resolves the crash on non
TurboFan platforms

BUG=
R=titzer@chromium.org

Review URL: https://codereview.chromium.org/618043002

Patch from Andrew Low <andrew_low@ca.ibm.com>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24424 ce2b1a6d-e550-0410-aec6-3dcde31c8c00