LoongArch Port: gcc build

2022-03-29  Chenghua Xu  <xuchenghua@loongson.cn>
	    Lulu Cheng  <chenglulu@loongson.cn>

gcc/ChangeLog:

	* common/config/loongarch/loongarch-common.cc: New file.
	* config/loongarch/genopts/genstr.sh: New file.
	* config/loongarch/genopts/loongarch-strings: New file.
	* config/loongarch/genopts/loongarch.opt.in: New file.
	* config/loongarch/loongarch-str.h: New file.
	* config/loongarch/gnu-user.h: New file.
	* config/loongarch/linux.h: New file.
	* config/loongarch/loongarch-cpu.cc: New file.
	* config/loongarch/loongarch-cpu.h: New file.
	* config/loongarch/loongarch-def.c: New file.
	* config/loongarch/loongarch-def.h: New file.
	* config/loongarch/loongarch-driver.cc: New file.
	* config/loongarch/loongarch-driver.h: New file.
	* config/loongarch/loongarch-opts.cc: New file.
	* config/loongarch/loongarch-opts.h: New file.
	* config/loongarch/loongarch.opt: New file.
	* config/loongarch/t-linux: New file.
	* config/loongarch/t-loongarch: New file.
	* config.gcc: Add LoongArch support.
	* configure.ac: Add LoongArch support.

contrib/ChangeLog:

	* gcc_update (files_and_dependencies): Add
	  config/loongarch/loongarch.opt and config/loongarch/loongarch-str.h.