Replace unnecessary ARM uses of <sys/linux-syscalls.h> with <asm/unistd.h>.

For some reason, socketcalls.c was only being compiled for ARM, where
it makes no sense. For x86 we generate stubs for the socket functions
that use __NR_socketcall directly.

Change-Id: I84181e6183fae2314ae3ed862276eba82ad21e8e
diff --git a/libc/arch-arm/bionic/futex_arm.S b/libc/arch-arm/bionic/futex_arm.S
index bbd0629..e21a385 100644
--- a/libc/arch-arm/bionic/futex_arm.S
+++ b/libc/arch-arm/bionic/futex_arm.S
@@ -26,7 +26,7 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/linux-syscalls.h>
+#include <asm/unistd.h>
 #include <machine/asm.h>
 
 #define FUTEX_WAIT 0