rs6000: Handle some recent MMA builtin changes

Peter Bergner recently added two new builtins __builtin_vsx_lxvp and
__builtin_vsx_stxvp.  These happened to break a pattern in MMA builtins that
I had been using to automate gimple folding of MMA builtins.  Previously,
every MMA function that could be folded had an associated internal function
that it was folded into.  The LXVP/STXVP builtins are just folded directly
into memory operations.

Instead of relying on this pattern, this patch adds a new attribute to
builtins called "mmaint," which is set for all MMA builtins that have an
associated internal builtin.  The naming convention that adds _INTERNAL to
the builtin index name remains.

The rest of the patch is just duplicating Peter's patch, using the new
builtin infrastructure.

2021-09-17  Bill Schmidt  <wschmidt@linux.ibm.com>

gcc/
	* config/rs6000/rs6000-builtin-new.def (ASSEMBLE_ACC): Add mmaint flag.
	(ASSEMBLE_PAIR): Likewise.
	(BUILD_ACC): Likewise.
	(DISASSEMBLE_ACC): Likewise.
	(DISASSEMBLE_PAIR): Likewise.
	(PMXVBF16GER2): Likewise.
	(PMXVBF16GER2NN): Likewise.
	(PMXVBF16GER2NP): Likewise.
	(PMXVBF16GER2PN): Likewise.
	(PMXVBF16GER2PP): Likewise.
	(PMXVF16GER2): Likewise.
	(PMXVF16GER2NN): Likewise.
	(PMXVF16GER2NP): Likewise.
	(PMXVF16GER2PN): Likewise.
	(PMXVF16GER2PP): Likewise.
	(PMXVF32GER): Likewise.
	(PMXVF32GERNN): Likewise.
	(PMXVF32GERNP): Likewise.
	(PMXVF32GERPN): Likewise.
	(PMXVF32GERPP): Likewise.
	(PMXVF64GER): Likewise.
	(PMXVF64GERNN): Likewise.
	(PMXVF64GERNP): Likewise.
	(PMXVF64GERPN): Likewise.
	(PMXVF64GERPP): Likewise.
	(PMXVI16GER2): Likewise.
	(PMXVI16GER2PP): Likewise.
	(PMXVI16GER2S): Likewise.
	(PMXVI16GER2SPP): Likewise.
	(PMXVI4GER8): Likewise.
	(PMXVI4GER8PP): Likewise.
	(PMXVI8GER4): Likewise.
	(PMXVI8GER4PP): Likewise.
	(PMXVI8GER4SPP): Likewise.
	(XVBF16GER2): Likewise.
	(XVBF16GER2NN): Likewise.
	(XVBF16GER2NP): Likewise.
	(XVBF16GER2PN): Likewise.
	(XVBF16GER2PP): Likewise.
	(XVF16GER2): Likewise.
	(XVF16GER2NN): Likewise.
	(XVF16GER2NP): Likewise.
	(XVF16GER2PN): Likewise.
	(XVF16GER2PP): Likewise.
	(XVF32GER): Likewise.
	(XVF32GERNN): Likewise.
	(XVF32GERNP): Likewise.
	(XVF32GERPN): Likewise.
	(XVF32GERPP): Likewise.
	(XVF64GER): Likewise.
	(XVF64GERNN): Likewise.
	(XVF64GERNP): Likewise.
	(XVF64GERPN): Likewise.
	(XVF64GERPP): Likewise.
	(XVI16GER2): Likewise.
	(XVI16GER2PP): Likewise.
	(XVI16GER2S): Likewise.
	(XVI16GER2SPP): Likewise.
	(XVI4GER8): Likewise.
	(XVI4GER8PP): Likewise.
	(XVI8GER4): Likewise.
	(XVI8GER4PP): Likewise.
	(XVI8GER4SPP): Likewise.
	(XXMFACC): Likewise.
	(XXMTACC): Likewise.
	(XXSETACCZ): Likewise.
	(ASSEMBLE_PAIR_V): Likewise.
	(BUILD_PAIR): Likewise.
	(DISASSEMBLE_PAIR_V): Likewise.
	(LXVP): New.
	(STXVP): New.
	* config/rs6000/rs6000-call.c (rs6000_gimple_fold_new_mma_builtin):
	Handle RS6000_BIF_LXVP and RS6000_BIF_STXVP.
	* config/rs6000/rs6000-gen-builtins.c (attrinfo): Add ismmaint.
	(parse_bif_attrs): Handle ismmaint.
	(write_decls): Add bif_mmaint_bit and bif_is_mmaint.
	(write_bif_static_init): Handle ismmaint.