arm: don't allow movMcc when short-it but no vsel [PR124134]

arm: don't allow movMcc when short-it but no vsel [PR124134]

Perverse combinations of options can lead to the compiler having to
work around unexpected situations.  Armv8 originally specified that
complex IT sequences were deprecated for performance (it was later
rescinded).  If the options restrict the floating-point unit to
one without vsel, then movMcc patterns need complex IT sequences
and we can end up with unmatched RTL patterns.  Avoid this by
failing early when the target patterns are disabled.

gcc/ChangeLog:

	PR target/124134
	* config/arm/arm.md (movsfcc): FAIL if using restricted IT
	blocks and we lack VSEL.
	(movdfcc): Likewise.

gcc/testsuite/ChangeLog:

	PR target/124134
	* gcc.target/arm/pr124134.c: New test.