libgomp/i386: Revert the type of syscall wrappers output back to long.

libgomp/i386: Revert the type of syscall wrappers output back to long.

Linux man-pages 5.07 wrongly declares syscall output type as int.  This error
was fixed in release 5.10, so this patch reverts my recent change.

2021-02-11  Uroš Bizjak  <ubizjak@gmail.com>

libgomp/
	* config/linux/x86/futex.h (__futex_wait):
	Revert output type back to long.
	(__futex_wake): Ditto.
	(futex_wait): Update for revert.
	(futex_wake): Ditto.