gimple-isel: Check whether IFN_VCONDEQ is supported [PR98560]

gimple-isel: Check whether IFN_VCONDEQ is supported [PR98560]

This patch follows on from the previous one for the PR and
makes sure that we can handle == as well as <.  Previously
we assumed without checking that IFN_VCONDEQ was available
if IFN_VCOND or IFN_VCONDU wasn't.

The patch also fixes the definition of the IFN_VCOND* functions.
The optabs are convert optabs in which the first mode is the
data mode and the second mode is the comparison or mask mode.

gcc/
	PR tree-optimization/98560
	* internal-fn.def (IFN_VCONDU, IFN_VCONDEQ): Use type vec_cond.
	* internal-fn.c (vec_cond_mask_direct): Get the data mode from
	argument 1.
	(vec_cond_direct): Likewise argument 2.
	(vec_condu_direct, vec_condeq_direct): Delete.
	(expand_vect_cond_optab_fn): Rename to...
	(expand_vec_cond_optab_fn): ...this, replacing old macro.
	(expand_vec_condu_optab_fn, expand_vec_condeq_optab_fn): Delete.
	(expand_vect_cond_mask_optab_fn): Rename to...
	(expand_vec_cond_mask_optab_fn): ...this, replacing old macro.
	(direct_vec_cond_mask_optab_supported_p): Treat the optab as a
	convert optab.
	(direct_vec_cond_optab_supported_p): Likewise.
	(direct_vec_condu_optab_supported_p): Delete.
	(direct_vec_condeq_optab_supported_p): Delete.
	* gimple-isel.cc: Include internal-fn.h.
	(gimple_expand_vec_cond_expr): Check that IFN_VCONDEQ is supported
	before using it.

gcc/testsuite/
	PR tree-optimization/98560
	* gcc.dg/vect/pr98560-2.c: New test.