MATCH: [PR111002] Sink view_convert for vec_cond

MATCH: [PR111002] Sink view_convert for vec_cond

Like convert we can sink view_convert into vec_cond but
we can only do it if the element types are nop_conversions.
This is to allow conversion between signed and unsigned types only.
Rather than between integer and float types which mess up the vec_cond
so that isel does not understand `a?-1:0` is still that.

OK? Bootstrapped and tested on x86_64-linux-gnu and aarch64-linux-gnu.

	PR tree-optimization/111002

gcc/ChangeLog:

	* match.pd (view_convert(vec_cond(a,b,c))): New pattern.

gcc/testsuite/ChangeLog:

	* gcc.target/aarch64/sve/cond_convert_8.c: New test.