Enable vect_float with S/390 VXE and adjust testcases

Enable vect_float with S/390 VXE and adjust testcases

The target supports routines provide vect_double and vect_float but
these do not appear to be used consequently in the vect testcases.
With z13 we only have support for vector double but with z14 also for
vector float.  This patch adds vect_float to the testcases using the
float data type and make the vect_float target check to return 1 only
on z14.

gcc/testsuite/ChangeLog:

2017-10-04  Andreas Krebbel  <krebbel@linux.vnet.ibm.com>

	* lib/target-supports.exp (check_effective_target_vect_float):
	Return 1 being on a S/390 with VXE.
	* gcc.dg/vect/pr31699.c: Require vec_float.
	* gcc.dg/vect/pr61194.c: Likewise.
	* gcc.dg/vect/pr65947-10.c: Likewise.
	* gcc.dg/vect/pr66142.c: Likewise.
	* gcc.dg/vect/slp-10.c: Likewise.
	* gcc.dg/vect/slp-11c.c: Likewise.
	* gcc.dg/vect/slp-12b.c: Likewise.
	* gcc.dg/vect/slp-18.c: Likewise.
	* gcc.dg/vect/slp-33.c: Likewise.
	* gcc.dg/vect/slp-cond-2-big-array.c: Likewise.
	* gcc.dg/vect/slp-cond-2.c: Likewise.
	* gcc.dg/vect/vect-cond-10.c: Likewise.
	* gcc.dg/vect/vect-cond-8.c: Likewise.
	* gcc.dg/vect/vect-cond-9.c: Likewise.
	* gcc.dg/vect/vect-float-extend-1.c: Likewise.
	* gcc.dg/vect/vect-float-truncate-1.c: Likewise.

From-SVN: r253403