aarch64: Add support for Ampere-1B (-mcpu=ampere1b) CPU

aarch64: Add support for Ampere-1B (-mcpu=ampere1b) CPU

This patch adds initial support for Ampere-1B core.

The Ampere-1B core implements ARMv8.7 with the following (compiler
visible) extensions:
 - CSSC (Common Short Sequence Compression instructions),
 - MTE (Memory Tagging Extension)
 - SM3/SM4

gcc/ChangeLog:

	* config/aarch64/aarch64-cores.def (AARCH64_CORE): Add ampere-1b
	* config/aarch64/aarch64-cost-tables.h: Add ampere1b_extra_costs
	* config/aarch64/aarch64-tune.md: Regenerate
	* config/aarch64/aarch64.cc: Include ampere1b tuning model
	* doc/invoke.texi: Document -mcpu=ampere1b
	* config/aarch64/tuning_models/ampere1b.h: New file.