[PATCH] asm/generic: fix bug - kernel fails to build when enable some common audit code on Blackfin

If you enable some common audit code, the kernel fails to build.

In file included from lib/audit.c:17:
include/asm-generic/audit_write.h:3: error: '__NR_swapon' undeclared here (not in a function)
make[1]: *** [lib/audit.o] Error 1
make: *** [lib] Error 2

So do not use __NR_swapon if it isnt defined for a port.
Signed-off-by: NMike Frysinger <vapier.adi@gmail.com>
Signed-off-by: NBryan Wu <cooloney@kernel.org>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

include/asm-generic/audit_write.h

 #include <asm-generic/audit_dir_write.h>
 __NR_acct,
+#ifdef __NR_swapon
 __NR_swapon,
+#endif
 __NR_quotactl,
 __NR_truncate,
 #ifdef __NR_truncate64