[testsuite,4.7,committed]: fix gcc.c-torture/compile/pr52891-2.c

[Georg-Johann Lay]

Committed as obvious.

http://gcc.gnu.org/viewcvs?view=revision&revision=186775

Johann

        PR testsuite/52641
        PR tree-optimizations/52891
        * gcc.c-torture/compile/pr52891-2.c: Fix test for 16-bit int.