The SYS_ constants should cover all __NR_ values.

<sys/linux-syscalls.h> only contains constants for the syscalls
we're generating stubs for. We want all the syscalls available
on the architecture in question.

Keep using <sys/linux-syscalls.h> on ARM for now because the
__NR_ARM_set_tls and __NR_ARM_cacheflush values aren't in <asm/unistd.h>.

Change-Id: I66683950d87d9b18d6107d0acc0ed238a4496f44
diff --git a/libc/arch-arm/bionic/tkill.S b/libc/arch-arm/bionic/tkill.S
index d5bb739..fd6e21e 100644
--- a/libc/arch-arm/bionic/tkill.S
+++ b/libc/arch-arm/bionic/tkill.S
@@ -25,6 +25,11 @@
  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
+
+#include <linux/err.h>
+#include <asm/unistd.h>
+#include <machine/asm.h>
+
 /* unlike our auto-generated syscall stubs, this code saves lr
    on the stack, as well as a few other registers. this makes
    our stack unwinder happy, when we generate debug stack
@@ -33,14 +38,6 @@
    of a corrupted malloc heap).
 */
 
-#include <linux/err.h>
-#include <sys/linux-syscalls.h>
-#include <machine/asm.h>
-
-#ifndef __NR_tkill
-#define __NR_tkill  238
-#endif
-
 ENTRY(tkill)
     stmfd   sp!, {r4-r7, ip, lr}
     ldr     r7, =__NR_tkill