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/include/sys/glibc-syscalls.h b/libc/include/sys/glibc-syscalls.h
index 0deb73a..3131b6b 100644
--- a/libc/include/sys/glibc-syscalls.h
+++ b/libc/include/sys/glibc-syscalls.h
@@ -375,6 +375,7 @@
 #define SYS_fcntl64 __NR_fcntl64
 #define SYS_fdatasync __NR_fdatasync
 #define SYS_fgetxattr __NR_fgetxattr
+#define SYS_finit_module __NR_finit_module
 #define SYS_flistxattr __NR_flistxattr
 #define SYS_flock __NR_flock
 #define SYS_fork __NR_fork
@@ -439,6 +440,7 @@
 #define SYS_ioprio_get __NR_ioprio_get
 #define SYS_ioprio_set __NR_ioprio_set
 #define SYS_ipc __NR_ipc
+#define SYS_kcmp __NR_kcmp
 #define SYS_kexec_load __NR_kexec_load
 #define SYS_keyctl __NR_keyctl
 #define SYS_kill __NR_kill