[committed] RISC-V testsuite adjustments for c23

[committed] RISC-V testsuite adjustments for c23

Mix of fixes and workarounds by passing in -std=gnu17.  The former is the
preferred approach, but occasionally we have code that's just fugly to fix.

gcc/testsuite/
	* gcc.target/riscv/cmo-32.c: Pass in -std=gnu17.
	* gcc.target/riscv/cmo-64.c: Likewise.
	* gcc.target/riscv/pr98777.c: Likewise.
	* gcc.target/riscv/rvv/vsetvl/pr115214.c: Likewise.
	* gcc.target/riscv/rvv/autovec/pr113469.c: Likewise.
	* gcc.target/riscv/rvv/autovec/pr111391-1.c: Fix prototype for c23.
	* gcc.target/riscv/rvv/vsetvl/vsetvl_bug-1.c: Likewise.
	* gcc.target/riscv/sum-of-two-s12-const-2.c: Likewise.
	* gcc.target/riscv/target-attr-01.c: Likewise.
	* gcc.target/riscv/target-attr-02.c: Likewise.
	* gcc.target/riscv/target-attr-03.c: Likewise.
	* gcc.target/riscv/target-attr-04.c: Likewise.
	* gcc.target/riscv/target-attr-05.c: Likewise.
	* gcc.target/riscv/target-attr-06.c: Likewise.
	* gcc.target/riscv/target-attr-07.c: Likewise.
	* gcc.target/riscv/target-attr-08.c: Likewise.
	* gcc.target/riscv/target-attr-09.c: Likewise.
	* gcc.target/riscv/target-attr-10.c: Likewise.
	* gcc.target/riscv/target-attr-11.c: Likewise.
	* gcc.target/riscv/target-attr-12.c: Likewise.
	* gcc.target/riscv/target-attr-13.c: Likewise.
	* gcc.target/riscv/target-attr-14.c: Likewise.
	* gcc.target/riscv/target-attr-15.c: Likewise.
	* gcc.target/riscv/target-attr-bad-01.c: Likewise.
	* gcc.target/riscv/target-attr-bad-02.c: Likewise.
	* gcc.target/riscv/target-attr-bad-03.c: Likewise.
	* gcc.target/riscv/target-attr-bad-04.c: Likewise.
	* gcc.target/riscv/target-attr-bad-05.c: Likewise.
	* gcc.target/riscv/target-attr-bad-06.c: Likewise.
	* gcc.target/riscv/target-attr-bad-07.c: Likewise.
	* gcc.target/riscv/target-attr-bad-08.c: Likewise.
	* gcc.target/riscv/target-attr-bad-09.c: Likewise.
	* gcc.target/riscv/target-attr-bad-10.c: Likewise.