deref_check: use in_macro() to silence most of the output

deref_check: use in_macro() to silence most of the output

I actually think check_deref_check.c is OK.  For the kernel you can use
smatch_scripts/filter_kernel_deref_check.sh to remove most of the false
positives.

On the other hand, most people don't know about that and anyway it's a bit
awkward.

If you want the old information then use option --spammy.

Signed-off-by: Dan Carpenter <error27@gmail.com>