re PR target/34900 (target mips64vrel-elf. Internal compiler error (in reload_cse_simplify_operands, at postreload.c:392) while building libiberty)

gcc/
	PR target/34900
	* config/mips/mips.c (gen_load_const_gp): New function, taking a
	comment from...
	(mips16_gp_pseudo_reg): ...here.
	* config/mips/mips.md (load_const_gp): Replace with...
	(load_const_gp_<mode>): ...this :P-based insn.

From-SVN: r131983