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-mips/syscalls/recvfrom.S b/libc/arch-mips/syscalls/recvfrom.S
index cf3441d..c34e506 100644
--- a/libc/arch-mips/syscalls/recvfrom.S
+++ b/libc/arch-mips/syscalls/recvfrom.S
@@ -1,5 +1,5 @@
 /* autogenerated by gensyscalls.py */
-#include <sys/linux-syscalls.h>
+#include <asm/unistd.h>
     .text
     .globl recvfrom
     .align 4