timer_create.2: SYNOPSIS: Use 'restrict' in prototypes

timer_create.2: SYNOPSIS: Use 'restrict' in prototypes

POSIX specifies that the parameters of timer_create()
shall be 'restrict'.  Glibc uses 'restrict' too.
Let's use it here too.

......

.../glibc$ grep_glibc_prototype timer_create
time/time.h:234:
extern int timer_create (clockid_t __clock_id,
			 struct sigevent *__restrict __evp,
			 timer_t *__restrict __timerid) __THROW;
.../glibc$

Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>