LoongArch: Define builtin macros for ISA evolutions

LoongArch: Define builtin macros for ISA evolutions

Detailed description of these definitions can be found at
https://github.com/loongson/la-toolchain-conventions, which
the LoongArch GCC port aims to conform to.

gcc/ChangeLog:

	* config.gcc: Add loongarch-evolution.o.
	* config/loongarch/genopts/genstr.sh: Enable generation of
	loongarch-evolution.[cc,h].
	* config/loongarch/t-loongarch: Likewise.
	* config/loongarch/genopts/gen-evolution.awk: New file.
	* config/loongarch/genopts/isa-evolution.in: Mark ISA version
	of introduction for each ISA evolution feature.
	* config/loongarch/loongarch-c.cc (loongarch_cpu_cpp_builtins):
	Define builtin macros for enabled ISA evolutions and the ISA
	version.
	* config/loongarch/loongarch-cpu.cc: Use loongarch-evolution.h.
	* config/loongarch/loongarch.h: Likewise.
	* config/loongarch/loongarch-cpucfg-map.h: Delete.
	* config/loongarch/loongarch-evolution.cc: New file.
	* config/loongarch/loongarch-evolution.h: New file.
	* config/loongarch/loongarch-opts.h (ISA_HAS_FRECIPE): Define.
	(ISA_HAS_DIV32): Likewise.
	(ISA_HAS_LAM_BH): Likewise.
	(ISA_HAS_LAMCAS): Likewise.
	(ISA_HAS_LD_SEQ_SA): Likewise.