rs6000: Built-in cleanups for vec_clzm, vec_ctzm, and vec_gnb

rs6000: Built-in cleanups for vec_clzm, vec_ctzm, and vec_gnb

Changes to the built-in specification occurred after early patches
added support for these.  The name of vec_clzm became vec_cntlzm,
and vec_ctzm became vec_cnttzm.  Four of the overloaded forms of
vec_gnb were removed, and the fourth argument redefined as an
unsigned int, not an unsigned char.  This patch reflects those
changes in the code and test cases.  Eight of the vec_gnb test
cases are removed as a result.

[gcc]

2020-05-11  Kelvin Nilsen  <kelvin@gcc.gnu.org>

	* config/rs6000/altivec.h (vec_clzm): Rename to vec_cntlzm.
	(vec_ctzm): Rename to vec_cnttzm.
	* config/rs6000/rs6000-c.c (altivec_resolve_overloaded_builtin):
	Change fourth operand for vec_ternarylogic to require
	compatibility with unsigned SImode rather than unsigned QImode.
	* config/rs6000/rs6000-call.c (altivec_overloaded_builtins):
	Remove overloaded forms of vec_gnb that are no longer needed.
	* doc/extend.texi (PowerPC AltiVec Built-in Functions Available
	for a Future Architecture): Replace vec_clzm with vec_cntlzm;
	replace vec_ctzm with vec_cntlzm; remove four unwanted forms of
	vec_gnb; move vec_ternarylogic documentation into this section
	and replace const unsigned char with const unsigned int as its
	fourth argument.

[gcc/testsuite]

2020-05-11  Kelvin Nilsen  <kelvin@gcc.gnu.org>

	* gcc.target/powerpc/vec-clzm-0.c: Rename to...
	* gcc.target/powerpc/vec-cntlzm-0.c: ...this.
	* gcc.target/powerpc/vec-clzm-1.c: Rename to...
	* gcc.target/powerpc/vec-cntlzm-1.c: ...this.
	* gcc.target/powerpc/vec-ctzm-0.c: Rename to...
	* gcc.target/powerpc/vec-cnttzm-0.c: ...this.
	* gcc.target/powerpc/vec-ctzm-1.c: Rename to...
	* gcc.target/powerpc/vec-cnttzm-1.c: ...this.
	* gcc.target/powerpc/vec-gnb-8.c: Rename to...
	* gcc.target/powerpc/vec-gnb-0.c: ...this, deleting the old file.
	* gcc.target/powerpc/vec-gnb-9.c: Rename to...
	* gcc.target/powerpc/vec-gnb-1.c: ...this, deleting the old file.
	* gcc.target/powerpc/vec-gnb-10.c: Rename to...
	* gcc.target/powerpc/vec-gnb-2.c: ...this, deleting the old file.
	* gcc.target/powerpc/vec-gnb-3.c: Delete.
	* gcc.target/powerpc/vec-gnb-4.c: Delete.
	* gcc.target/powerpc/vec-gnb-5.c: Delete.
	* gcc.target/powerpc/vec-gnb-6.c: Delete.
	* gcc.target/powerpc/vec-gnb-7.c: Delete.