Fix incorrect relocations for x86.

These calls were not going through the PLT like they should have been.

Bug: 16853291
Change-Id: Id70488b077256a70137c4417f21be2c2d1d4341c
diff --git a/libc/arch-x86/syscalls/setuid.S b/libc/arch-x86/syscalls/setuid.S
index fcea66d..45747ff 100644
--- a/libc/arch-x86/syscalls/setuid.S
+++ b/libc/arch-x86/syscalls/setuid.S
@@ -13,7 +13,7 @@
     jb      1f
     negl    %eax
     pushl   %eax
-    call    __set_errno
+    call    PIC_PLT(__set_errno)
     addl    $4, %esp
 1:
     popl    %ebx