Switch sigpending over to rt_sigpending.

Change-Id: I7b28984796b5fb343cfbcc47e0afc3a84293d417
diff --git a/libc/arch-x86/syscalls.mk b/libc/arch-x86/syscalls.mk
index 10970a6..698f6f5 100644
--- a/libc/arch-x86/syscalls.mk
+++ b/libc/arch-x86/syscalls.mk
@@ -3,10 +3,10 @@
 syscall_src += arch-x86/syscalls/_exit.S
 syscall_src += arch-x86/syscalls/_exit_thread.S
 syscall_src += arch-x86/syscalls/__fork.S
-syscall_src += arch-x86/syscalls/_waitpid.S
-syscall_src += arch-x86/syscalls/__waitid.S
 syscall_src += arch-x86/syscalls/wait4.S
 syscall_src += arch-x86/syscalls/__sys_clone.S
+syscall_src += arch-x86/syscalls/_waitpid.S
+syscall_src += arch-x86/syscalls/__waitid.S
 syscall_src += arch-x86/syscalls/execve.S
 syscall_src += arch-x86/syscalls/getuid.S
 syscall_src += arch-x86/syscalls/getgid.S
@@ -156,8 +156,8 @@
 syscall_src += arch-x86/syscalls/timerfd_settime.S
 syscall_src += arch-x86/syscalls/timerfd_gettime.S
 syscall_src += arch-x86/syscalls/sigaction.S
-syscall_src += arch-x86/syscalls/sigpending.S
 syscall_src += arch-x86/syscalls/__rt_sigaction.S
+syscall_src += arch-x86/syscalls/__rt_sigpending.S
 syscall_src += arch-x86/syscalls/__rt_sigprocmask.S
 syscall_src += arch-x86/syscalls/__rt_sigsuspend.S
 syscall_src += arch-x86/syscalls/__rt_sigtimedwait.S