rs6000.c (rs6000_gimple_fold_builtin): Add handling for early expansion of vector absolute builtins.

[gcc]

2017-05-31  Will Schmidt  <will_schmidt@vnet.ibm.com>

	* config/rs6000/rs6000.c (rs6000_gimple_fold_builtin): Add handling
	for early expansion of vector absolute builtins.

[gcc/testsuite]

2017-05-31  Will Schmidt  <will_schmidt@vnet.ibm.com>

	* gcc.target/powerpc/fold-vec-abs-char.c: New.
	* gcc.target/powerpc/fold-vec-abs-floatdouble.c: New.
	* gcc.target/powerpc/fold-vec-abs-int.c: New.
	* gcc.target/powerpc/fold-vec-abs-longlong.c: New.
	* gcc.target/powerpc/fold-vec-abs-short.c: New.
	* gcc.target/powerpc/fold-vec-abs-char-fwrapv.c: New.
	* gcc.target/powerpc/fold-vec-abs-int-fwrapv.c: New.
	* gcc.target/powerpc/fold-vec-abs-longlong-fwrapv.c: New.
	* gcc.target/powerpc/fold-vec-abs-short-fwrapv.c: New.

From-SVN: r248830