Fix autofs compile without CONFIG_COMPAT

The autofs compat handling fix caused a compile failure when
CONFIG_COMPAT isn't defined.

Instead of adding random #ifdef'fery in autofs, let's just make the
compat helpers earlier to use: without CONFIG_COMPAT, is_compat_task()
just hardcodes to zero.

We could probably do something similar for a number of other cases where
we have #ifdef's in code, but this is the low-hanging fruit.

Reported-and-tested-by: Andreas Schwab <schwab@linux-m68k.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/compat.h

@@ -561,5 +561,9 @@ asmlinkage ssize_t compat_sys_process_vm_writev(compat_pid_t pid,
 		unsigned long liovcnt, const struct compat_iovec __user *rvec,
 		unsigned long riovcnt, unsigned long flags);
 
+#else
+
+#define is_compat_task() (0)
+
 #endif /* CONFIG_COMPAT */
 #endif /* _LINUX_COMPAT_H */