patch fixing a test for PR55151

[Vladimir Makarov]

  The following patch adds omitted target for the test.  The test was 
supposed to run on x86-64 only.  On 32-bit x86, it should fail.  Reload 
fails on this test on x86 too although with an error message.  I am 
going to add a generation of a message too.

  Committed as rev. 193311.
2012-11-07  Vladimir Makarov  <vmaka...@redhat.com>

        PR rtl-optimization/55151
        * gcc.dg/pr55151.c: Compile it only for x86_64.