[PATCH, testsuite] Enable vect_usad_char effective target for PowerPC and fix up SAD_EXPR testcases

[Jeff Law]

On 2/19/19 2:07 PM, Pat Haugen wrote:
> Power9 added support for V16QImode SAD operations. While making the check_effective_target change I noticed that the tests will also pass on Power7/Power8 even though they don't have the optab support. The reason is the tests are only checking that the source pattern is recognized, not that a SAD_EXPR was actually generated. So I've updated the tests also.
> 
> Ok for trunk?
> 
> -Pat
> 
> 
> testsuite/ChangeLog:
> 2019-02-19  Pat Haugen  <pthaugen@us.ibm.com>
> 
> 	* lib/target-supports.exp (check_effective_target_vect_usad_char):
> 	Add PowerPC support.
> 	* gcc.dg/vect/slp-reduc-sad.c: Update scan string.
> 	* gcc.dg/vect/vect-reduc-sad.c: Likewise.
OK
jeff