[PATCH]rs6000,testsuite Add a powerpc64-prologue testcase.

Add a powerpc64-prologue testcase, this is based on the existing
powerpc-prologue test, but updated for the powerpc64 (le) target.

YYYY-MM-DD  Will Schmidt  <will_schmidt@vnet.ibm.com>

gcc/testsuite/ChangeLog
	* gdb.arch/powerpc64-prologue.c: New test to exercise prologues
	for the powerpc64 LE target.
	* gdb.arch/powerpc-prologue.exp: Test Harness.