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-x86/syscalls/getpid.S b/libc/arch-x86/syscalls/getpid.S
index 3f4406e..f9e3613 100644
--- a/libc/arch-x86/syscalls/getpid.S
+++ b/libc/arch-x86/syscalls/getpid.S
@@ -1,7 +1,7 @@
 /* autogenerated by gensyscalls.py */
 #include <linux/err.h>
 #include <machine/asm.h>
-#include <sys/linux-syscalls.h>
+#include <asm/unistd.h>
 
 ENTRY(getpid)
     movl    $__NR_getpid, %eax