RISC-V: Implement ZBKB, ZBKC and ZBKX extensions

This patch supports Zkbk, Zbkc and Zkbx extension.
It includes instruction's machine description and built-in funtions.
It is worth mentioning that this patch only adds instructions in Zbkb but no
longer in Zbb.
If any instructions both in Zbb and Zbkb, they will be generated by code
generator instead of built-in functions.

gcc/ChangeLog:

	* config/riscv/bitmanip.md: Add ZBKB's instructions.
	* config/riscv/riscv-builtins.cc (AVAIL): Add new.
	* config/riscv/riscv.md: Add new type for crypto instructions.
	* config/riscv/crypto.md: Add Scalar Cryptography extension's machine
	description file.
	* config/riscv/riscv-scalar-crypto.def: Add Scalar Cryptography
	extension's built-in function file.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/zbkb32.c: New test.
	* gcc.target/riscv/zbkb64.c: New test.
	* gcc.target/riscv/zbkc32.c: New test.
	* gcc.target/riscv/zbkc64.c: New test.
	* gcc.target/riscv/zbkx32.c: New test.
	* gcc.target/riscv/zbkx64.c: New test.

Co-Authored-By: SiYu Wu <siyu@isrc.iscas.ac.cn>