Add Zc* test for march args being passed.

	* gcc.target/riscv/zc-zca-arch.c: New test for march args
	being passed from compiler to assembler.
	* gcc.target/riscv/zc-zcb-arch.c: Likewise.
	* gcc.target/riscv/zc-zcb-m-arch.c: Likewise.
	* gcc.target/riscv/zc-zcb-zba-arch.c: Likewise.
	* gcc.target/riscv/zc-zcf-arch.c: Likewise.
	* gcc.target/riscv/zc-zcf-zbb-arch.c: Likewise.
	* gcc.target/riscv/zc-zcmb-arch.c: Likewise.
	* gcc.target/riscv/zc-zcmp-arch.c: Likewise.
	* gcc.target/riscv/zc-zcmpe-arch.c: Likewise.
	* gcc.target/riscv/zc-zcmt-arch.c: Likewise.