Clean up <sched.h>.

This patch switches to using the uapi constants. It also adds the missing
setns system call, fixes sched_getcpu's error behavior, and fixes the
gensyscalls script now ARM is uapi-only too.

Change-Id: I8e16b1693d6d32cd9b8499e46b5d8b0a50bc4f1d
diff --git a/libc/arch-x86/syscalls.mk b/libc/arch-x86/syscalls.mk
index 780972f..0699d09 100644
--- a/libc/arch-x86/syscalls.mk
+++ b/libc/arch-x86/syscalls.mk
@@ -153,6 +153,7 @@
 syscall_src += arch-x86/syscalls/setgid.S
 syscall_src += arch-x86/syscalls/setgroups.S
 syscall_src += arch-x86/syscalls/setitimer.S
+syscall_src += arch-x86/syscalls/setns.S
 syscall_src += arch-x86/syscalls/setpgid.S
 syscall_src += arch-x86/syscalls/setpriority.S
 syscall_src += arch-x86/syscalls/setregid.S
diff --git a/libc/arch-x86/syscalls/setns.S b/libc/arch-x86/syscalls/setns.S
new file mode 100644
index 0000000..6bdb98c
--- /dev/null
+++ b/libc/arch-x86/syscalls/setns.S
@@ -0,0 +1,23 @@
+/* Generated by gensyscalls.py. Do not edit. */
+
+#include <private/bionic_asm.h>
+
+ENTRY(setns)
+    pushl   %ebx
+    pushl   %ecx
+    mov     12(%esp), %ebx
+    mov     16(%esp), %ecx
+    movl    $__NR_setns, %eax
+    int     $0x80
+    cmpl    $-MAX_ERRNO, %eax
+    jb      1f
+    negl    %eax
+    pushl   %eax
+    call    __set_errno
+    addl    $4, %esp
+    orl     $-1, %eax
+1:
+    popl    %ecx
+    popl    %ebx
+    ret
+END(setns)