s390x: Fix fmin/fmax patterns

s390x: Fix fmin/fmax patterns

s390x floating point minimum and maximum functions unfortunately do
not canonicalize NaNs.  Hence, test pr105414.c fails since
c476f554e3f.  Fix this by only allowing fmin/fmax pattern if signaling
NaNs are disabled.

gcc/ChangeLog:

	* config/s390/vector.md (fmax<mode>3): Restrict to no trapping
	math.
	(fmin<mode>3): Ditto.

gcc/testsuite/ChangeLog:

	* gcc.target/s390/fminmax-1.c: Disable for signaling NaNs.
	* gcc.target/s390/fminmax-2.c: Ditto.
	* gcc.target/s390/vector/reduc-minmax-1.c: Ditto.

Signed-off-by: Juergen Christ <jchrist@linux.ibm.com>