rs6000: Tune new testcase (PR83629)

It has some problems running on some 64-bit configuratiions, and the
bug it is testing for is only on 32-bit; so let's not run it elsewhere.


gcc/testsuite/
	PR target/83629
	* gcc.target/powerpc/pr83629.c: Require ilp32.

From-SVN: r256577

gcc/testsuite/ChangeLog

+2018-01-12  Segher Boessenkool  <segher@kernel.crashing.org>
+
+	PR target/83629
+	* gcc.target/powerpc/pr83629.c: Require ilp32.
+
 2018-01-12  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/80846

gcc/testsuite/gcc.target/powerpc/pr83629.c

+/* { dg-require-effective-target ilp32 } */
 /* { dg-options "-O2 -fPIC -frename-registers --param=sched-autopref-queue-depth=0 -mcpu=603" } */
 
 extern void bar (void *);