Move the target support routine for the vector facility to the common
code file.  This is required to enable the generic vectorization tests
on S/390.  While doing this the too generic name for the check (vector)
is changed to s390_vx.  The renaming required to modify all the
testcases currently using that check.

gcc/testsuite/ChangeLog:

2017-03-24  Andreas Krebbel  <krebbel@linux.vnet.ibm.com>

	* gcc.target/s390/s390.exp (check_effective_target_vector):
	Include target-supports.exp and move target_vector check routine
	...
	* lib/target-supports.exp (check_effective_target_s390_vx): ... to
	here and rename it.
	* gcc.target/s390/htm-builtins-z13-1.c: Rename effective target
	check from vector to s390_vx.
	* gcc.target/s390/target-attribute/tpragma-struct-vx-1.c: Likewise.
	* gcc.target/s390/target-attribute/tpragma-struct-vx-2.c: Likewise.
	* gcc.target/s390/vector/stpcpy-1.c: Likewise.
	* gcc.target/s390/vector/vec-abi-vararg-1.c: Likewise.
	* gcc.target/s390/vector/vec-clobber-1.c: Likewise.
	* gcc.target/s390/vector/vec-genbytemask-1.c: Likewise.
	* gcc.target/s390/vector/vec-genmask-1.c: Likewise.
	* gcc.target/s390/vector/vec-nopeel-1.c: Likewise.
	* gcc.target/s390/vector/vec-vrepi-1.c: Likewise.

From-SVN: r246449