Fold: Fix up merge_truthop_with_opposite_arm for NaNs [PR95351]

Fold: Fix up merge_truthop_with_opposite_arm for NaNs [PR95351]

The problem here is that merge_truthop_with_opposite_arm would
use the type of the result of the comparison rather than the operands
of the comparison to figure out if we are honoring NaNs.
This fixes that oversight and now we get the correct results in this
case.

Committed as obvious after a bootstrap/test on x86_64-linux-gnu.

	PR middle-end/95351

gcc/ChangeLog:

	* fold-const.cc (merge_truthop_with_opposite_arm): Use
	the type of the operands of the comparison and not the type
	of the comparison.

gcc/testsuite/ChangeLog:

	* gcc.dg/float_opposite_arm-1.c: New test.

Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>
(cherry picked from commit 31ce2e993d09dcad1ce139a2848a28de5931056d)