PR target/80482

This patch changes the parameter testing for powerpc vector builtins to relax
the existing requirement that the parameters be identical to instead that they
be compatible.  This allows for mixing parameters with differing qualified
(const, volatile, etc.) types.

See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80482 for more information.

Bootstrapped and tested on powerpc64le-unknown-linux-gnu and
powerpc64be-unknown-linux-gnu with no regressions.  Is this ok for trunk?

[gcc]

2017-04-25  Bill Seurer  <seurer@linux.vnet.ibm.com>

	PR target/80482
	* config/rs6000/rs6000-c.c (altivec_resolve_overloaded_builtin): Change
	type checks to test for compatibility instead of equality.

[gcc/testsuite]

2017-04-25  Bill Seurer  <seurer@linux.vnet.ibm.com>

	PR target/80482
	* gcc.target/powerpc/vec-constvolatile.c: New test.

From-SVN: r247250