S/390: Fix vecinit expansion.

S/390: Fix vecinit expansion.

The fallback routine in the S/390 vecinit expander did not check
whether each of the initializer elements is a proper general_operand.
Since revision r236582 the expander is invoked also with e.g. symbol
refs with an odd addend resulting in invalid insns.

Fixed by forcing the element into a register in such cases.

gcc/ChangeLog:

2016-07-06  Andreas Krebbel  <krebbel@linux.vnet.ibm.com>

	* config/s390/s390.c (s390_expand_vec_init): Force initializer
	element to register if it doesn't match general_operand.

From-SVN: r238032