middle-end: don't lower past veclower [PR106063]

middle-end: don't lower past veclower [PR106063]

Hi All,

My previous patch can cause a problem if the pattern matches after veclower
as it may replace the construct with a vector sequence which the target may not
directly support.

As such don't perform the rewriting if after veclower unless the target supports
the operation.  If before veclower do the rewriting as well if the target didn't
support the original operation either.

gcc/ChangeLog:

	PR tree-optimization/106063
	* match.pd: Do not apply pattern after veclower is not supported.

gcc/testsuite/ChangeLog:

	PR tree-optimization/106063
	* gcc.dg/pr106063.c: New test.