[RS6000] Tests that use int128_t and -m32

[RS6000] Tests that use int128_t and -m32

All these tests fail with -m32 due to lack of int128 support, in some
cases with what I thought was not the best error message.  For example
vsx_mask-move-runnable.c:34:3: error: unknown type name 'vector'
is misleading.  The problem isn't "vector" but "vector __uint128_t".

	* gcc.target/powerpc/vsx-load-element-extend-char.c: Require int128.
	* gcc.target/powerpc/vsx-load-element-extend-int.c: Likewise.
	* gcc.target/powerpc/vsx-load-element-extend-longlong.c: Likewise.
	* gcc.target/powerpc/vsx-load-element-extend-short.c: Likewise.
	* gcc.target/powerpc/vsx-store-element-truncate-char.c: Likewise.
	* gcc.target/powerpc/vsx-store-element-truncate-int.c: Likewise.
	* gcc.target/powerpc/vsx-store-element-truncate-longlong.c: Likewise.
	* gcc.target/powerpc/vsx-store-element-truncate-short.c: Likewise.
	* gcc.target/powerpc/vsx_mask-count-runnable.c: Likewise.
	* gcc.target/powerpc/vsx_mask-expand-runnable.c: Likewise.
	* gcc.target/powerpc/vsx_mask-extract-runnable.c: Likewise.
	* gcc.target/powerpc/vsx_mask-move-runnable.c: Likewise.