altivec.h: Add builtin names vec_extract4b vec_insert4b.

altivec.h: Add builtin names vec_extract4b vec_insert4b.

gcc/ChangeLog:

2018-02-16  Carl Love  <cel@us.ibm.com>

	* config/rs6000/altivec.h: Add builtin names vec_extract4b
	vec_insert4b.
	* config/rs6000/rs6000-builtin.def: Add INSERT4B and EXTRACT4B
	definitions.
	* config/rs6000/rs6000-c.c: Add the definitions for
	P9V_BUILTIN_VEC_EXTRACT4B and P9V_BUILTIN_VEC_INSERT4B.
	* config/rs6000/rs6000.c (altivec_expand_builtin): Add
	P9V_BUILTIN_EXTRACT4B and P9V_BUILTIN_INSERT4B case statements.
	* config/rs6000/vsx.md: Add define_insn extract4b.  Add define_expand
	definition for insert4b and define insn *insert3b_internal.
	* doc/extend.texi: Add documentation for vec_extract4b.

gcc/testsuite/ChangeLog:

2018-02-16  Carl Love  <cel@us.ibm.com>
	* gcc.target/powerpc/builtins-7-p9-runnable.c: New runnable test file
	for the ABI definitions for vec_extract4b and vec_insert4b.

From-SVN: r257747