Built-in initialization occurs only once and fairly early, when the
command line options are in force.  If the -mcpu=<CPU> is pre-power10,
then we fail to initialize the MMA built-ins, so they are not
available to call in a #pragma target/attribute target function.
The fix is to basically always (on server type cpus) initialize the MMA
built-ins so we can use them in #pragma target/attribute target functions.

2020-07-09  Peter Bergner  <bergner@linux.ibm.com>

gcc/
	PR target/96125
	* config/rs6000/rs6000-call.c (rs6000_init_builtins): Define the MMA
	specific types __vector_quad and __vector_pair, and initialize the
	MMA built-ins if TARGET_EXTRA_BUILTINS is set.
	(mma_init_builtins): Don't test for mask set in rs6000_builtin_mask.
	Remove now unneeded mask variable.
	* config/rs6000/rs6000.c (rs6000_option_override_internal): Add the
	OPTION_MASK_MMA flag for power10 if not already set.

gcc/testsuite/
	PR target/96125
	* gcc.target/powerpc/pr96125.c: New test.

(cherry picked from commit fd263be4b523ff1b7f7dda49d856cc57221e8d21)