Expose wait4 as wait4 rather than __wait4.

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

Change-Id: I5296d0cfec5546709cda990abd705ad33d7c4626
diff --git a/libc/arch-mips/syscalls.mk b/libc/arch-mips/syscalls.mk
index 7e40c2e..0b8eccd 100644
--- a/libc/arch-mips/syscalls.mk
+++ b/libc/arch-mips/syscalls.mk
@@ -5,6 +5,7 @@
 syscall_src += arch-mips/syscalls/__fork.S
 syscall_src += arch-mips/syscalls/_waitpid.S
 syscall_src += arch-mips/syscalls/__waitid.S
+syscall_src += arch-mips/syscalls/wait4.S
 syscall_src += arch-mips/syscalls/__sys_clone.S
 syscall_src += arch-mips/syscalls/execve.S
 syscall_src += arch-mips/syscalls/__setuid.S
@@ -183,7 +184,6 @@
 syscall_src += arch-mips/syscalls/ioprio_set.S
 syscall_src += arch-mips/syscalls/ioprio_get.S
 syscall_src += arch-mips/syscalls/uname.S
-syscall_src += arch-mips/syscalls/__wait4.S
 syscall_src += arch-mips/syscalls/umask.S
 syscall_src += arch-mips/syscalls/__reboot.S
 syscall_src += arch-mips/syscalls/__syslog.S
diff --git a/libc/arch-mips/syscalls/__wait4.S b/libc/arch-mips/syscalls/wait4.S
similarity index 81%
rename from libc/arch-mips/syscalls/__wait4.S
rename to libc/arch-mips/syscalls/wait4.S
index 713b7cb..8e3d2dc 100644
--- a/libc/arch-mips/syscalls/__wait4.S
+++ b/libc/arch-mips/syscalls/wait4.S
@@ -1,11 +1,11 @@
 /* autogenerated by gensyscalls.py */
 #include <sys/linux-syscalls.h>
     .text
-    .globl __wait4
+    .globl wait4
     .align 4
-    .ent __wait4
+    .ent wait4
 
-__wait4:
+wait4:
     .set noreorder
     .cpload $t9
     li $v0, __NR_wait4
@@ -19,4 +19,4 @@
     j $t9
     nop
     .set reorder
-    .end __wait4
+    .end wait4