S/390: Disable scalar vector instructions with -mno-vx.

S/390: Disable scalar vector instructions with -mno-vx.

Although the scalar variants of the vector instructions aren't
actually vector instructions they are still executed in the vector
facility and therefore need to be disabled when disabling the facility
with -mno-vx.

Fixed with the attached patch.  Committed to head, GCC 6, and GCC 5
branches.

gcc/ChangeLog:

2016-05-10  Andreas Krebbel  <krebbel@linux.vnet.ibm.com>

	* config/s390/s390.md ("*vec_cmp<insn_cmp>df_cconly")
	("*fixuns_truncdfdi2_z13")
	("*fixuns_trunc<FP:mode><GPR:mode>2_z196")
	("*fix_truncdfdi2_bfp_z13", "*floatunsdidf2_z13")
	("*extendsfdf2_z13"): Replace TARGET_Z13 with TARGET_VX.

From-SVN: r236067