RISC-V: Regenerate opt urls

Regenerate riscv.opt.urls so the checked-in file regains
the trailing blank line emitted by regenerate-opt-urls.py.

gcc/ChangeLog:

	* config/riscv/riscv.opt.urls: Regenerate.

Signed-off-by: Christoph Müllner <christoph.muellner@vrull.eu>