Expose wait4 as wait4 rather than __wait4.

This helps strace(1) compile with one fewer hack.

Change-Id: I5296d0cfec5546709cda990abd705ad33d7c4626
diff --git a/libc/arch-x86/syscalls.mk b/libc/arch-x86/syscalls.mk
index e196c02..b4ad564 100644
--- a/libc/arch-x86/syscalls.mk
+++ b/libc/arch-x86/syscalls.mk
@@ -5,6 +5,7 @@
 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/execve.S
 syscall_src += arch-x86/syscalls/__setuid.S
@@ -184,7 +185,6 @@
 syscall_src += arch-x86/syscalls/ioprio_set.S
 syscall_src += arch-x86/syscalls/ioprio_get.S
 syscall_src += arch-x86/syscalls/uname.S
-syscall_src += arch-x86/syscalls/__wait4.S
 syscall_src += arch-x86/syscalls/umask.S
 syscall_src += arch-x86/syscalls/__reboot.S
 syscall_src += arch-x86/syscalls/__syslog.S
diff --git a/libc/arch-x86/syscalls/__wait4.S b/libc/arch-x86/syscalls/wait4.S
similarity index 95%
rename from libc/arch-x86/syscalls/__wait4.S
rename to libc/arch-x86/syscalls/wait4.S
index 57de4d9..e3bad3e 100644
--- a/libc/arch-x86/syscalls/__wait4.S
+++ b/libc/arch-x86/syscalls/wait4.S
@@ -3,7 +3,7 @@
 #include <machine/asm.h>
 #include <sys/linux-syscalls.h>
 
-ENTRY(__wait4)
+ENTRY(wait4)
     pushl   %ebx
     pushl   %ecx
     pushl   %edx
@@ -27,4 +27,4 @@
     popl    %ecx
     popl    %ebx
     ret
-END(__wait4)
+END(wait4)