Fix VIS3 assembler check and conditionalize testsuite on VIS3 support.

Fix VIS3 assembler check and conditionalize testsuite on VIS3 support.

gcc/

	PR 50655
	* configure.ac: Add .register directives to VIS3 test.
	* configure: Regenerate.

gcc/testsuite/

	PR 50655
	* gcc.target/sparc/sparc.exp: Add vis3 target test.
	* gcc.target/sparc/cmask.c: Use it.
	* gcc.target/sparc/fhalve.c: Likewise.
	* gcc.target/sparc/fnegop.c: Likewise.
	* gcc.target/sparc/fpadds.c: Likewise.
	* gcc.target/sparc/fshift.c: Likewise.
	* gcc.target/sparc/fucmp.c: Likewise.
	* gcc.target/sparc/lzd.c: Likewise.
	* gcc.target/sparc/vis3misc.c: Likewise.
	* gcc.target/sparc/xmul.c: Likewise.

From-SVN: r179667