The builtin was not correctly defined in the vecintrin.h header file.

gcc/testsuite/ChangeLog:

2017-10-09  Andreas Krebbel  <krebbel@linux.vnet.ibm.com>

	PR target/82463
	* gcc.target/s390/zvector/pr82463.c: New test.

gcc/ChangeLog:

2017-10-09  Andreas Krebbel  <krebbel@linux.vnet.ibm.com>

	PR target/82463
	* config/s390/vecintrin.h (vec_madd, vec_msub): Fix macro
	definitions.

From-SVN: r253543