Make all rt_sigtimedwait signatures match.

There's no change to the generated stubs, because the script only cares
that this is a pointer type, not what it's a pointer to.

Change-Id: I766720965f0f3d201fc90677a076b26870485377
diff --git a/libc/SYSCALLS.TXT b/libc/SYSCALLS.TXT
index e530293..0c59c92 100644
--- a/libc/SYSCALLS.TXT
+++ b/libc/SYSCALLS.TXT
@@ -232,7 +232,7 @@
 int     __rt_sigpending:rt_sigpending(sigset_t*, size_t)  all
 int     __rt_sigprocmask:rt_sigprocmask(int, const sigset_t*, sigset_t*, size_t)  all
 int     __rt_sigsuspend:rt_sigsuspend(const sigset_t*, size_t)  all
-int     __rt_sigtimedwait:rt_sigtimedwait(const sigset_t*, struct siginfo_t*, struct timespec_t*, size_t)  all
+int     __rt_sigtimedwait:rt_sigtimedwait(const sigset_t*, siginfo_t*, const timespec*, size_t)  all
 int     ___rt_sigqueueinfo:rt_sigqueueinfo(pid_t, int, siginfo_t*)  all
 int     __signalfd4:signalfd4(int, const sigset_t*, size_t, int)  all