RISC-V: Fix format-diag warning from improperly formatted url

RISC-V: Fix format-diag warning from improperly formatted url

gcc/ChangeLog:

	PR target/116152
	* config/riscv/riscv.cc (riscv_option_override): Fix url
	formatting.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/predef-9.c: Update testcase.

Co-authored-by: Jakub Jelinek <jakub@redhat.com>
Signed-off-by: Patrick O'Neill <patrick@rivosinc.com>