rs6000: Fix invalid address used in MMA built-in function

rs6000: Fix invalid address used in MMA built-in function

The mma_assemble_input_operand predicate is too lenient on the memory
operands it will accept, leading to an ICE when illegitimate addresses
are passed in.  The solution is to only accept memory operands with
addresses that are valid for quad word memory accesses.  The test case
is a minimized test case from the Eigen library.  The creduced test case
is very noisy with respect to warnings, so the test case has added -w to
silence them.

2021-02-11  Peter Bergner  <bergner@linux.ibm.com>

gcc/
	PR target/99041
	* config/rs6000/predicates.md (mma_assemble_input_operand): Restrict
	memory addresses that are legal for quad word accesses.

gcc/testsuite/
	PR target/99041
	* g++.target/powerpc/pr99041.C: New test.