Use the correct names for the __ARM_NR_* syscalls.

This lets us move all the ARM syscall stubs over to the kernel <asm/unistd.h>.
Our generated <sys/linux-syscalls.h> is now unused, but I'll remove that in a
later change.

Change-Id: Ie5ff2cc4abce1938576af7cbaef615a79c7f310d
diff --git a/libc/arch-arm/syscalls/__set_tls.S b/libc/arch-arm/syscalls/__set_tls.S
index 909c4b3..73142ba 100644
--- a/libc/arch-arm/syscalls/__set_tls.S
+++ b/libc/arch-arm/syscalls/__set_tls.S
@@ -1,11 +1,11 @@
 /* autogenerated by gensyscalls.py */
+#include <asm/unistd.h>
 #include <linux/err.h>
 #include <machine/asm.h>
-#include <sys/linux-syscalls.h>
 
 ENTRY(__set_tls)
     mov     ip, r7
-    ldr     r7, =__NR_ARM_set_tls
+    ldr     r7, =__ARM_NR_set_tls
     swi     #0
     mov     r7, ip
     cmn     r0, #(MAX_ERRNO + 1)