S/390: PR79893: Add diagnostics vec_load_bndry builtin.

S/390: PR79893: Add diagnostics vec_load_bndry builtin.

The boundary argument of the vec_load_bndry builtin needs to be
rewritten.  At that point it must be constant already.  The current
diagnostics in s390_expand_builtins is too late for this.  The patch
adds an additional check for that builtin which will be triggered
already during preprocessing.

Regression tested on s390x.

gcc/testsuite/ChangeLog:

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

	PR target/79893
	* gcc.target/s390/zvector/pr79893.c: New test.

gcc/ChangeLog:

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

	PR target/79893
	* config/s390/s390-c.c (s390_adjust_builtin_arglist): Issue an
	error if the boundary argument is not constant.

From-SVN: r246442