riscv: fix styling in ucontext header

	struct ucontext	 *uc_link;

	stack_t		  uc_stack;

	sigset_t	  uc_sigmask;

	/* There's some padding here to allow sigset_t to be expanded in the

	/*

	 * There's some padding here to allow sigset_t to be expanded in the

	 * future.  Though this is unlikely, other architectures put uc_sigmask

	 * at the end of this structure and explicitly state it can be

	 * expanded, so we didn't want to box ourselves in here. */

	 * expanded, so we didn't want to box ourselves in here.

	 */

	__u8		  __unused[1024 / 8 - sizeof(sigset_t)];

	/* We can't put uc_sigmask at the end of this structure because we need

	/*

	 * We can't put uc_sigmask at the end of this structure because we need

	 * to be able to expand sigcontext in the future.  For example, the

	 * vector ISA extension will almost certainly add ISA state.  We want

	 * to ensure all user-visible ISA state can be saved and restored via a

	 * ucontext, so we're putting this at the end in order to allow for

	 * infinite extensibility.  Since we know this will be extended and we

	 * assume sigset_t won't be extended an extreme amount, we're

	 * prioritizing this. */

	 * prioritizing this.

	 */

	struct sigcontext uc_mcontext;

};