show bug in logging: log_set_category_filter on DL* categories

Add a check to logging_test.c to show a bug: passing an internal DL* category
constant to log_set_category_filter() results in a negative array index and
undefined behavior. A sanitize build should catch this.

The bug is confirmed by the fact that logging_test.err stays the same
(hopefully) although a logging output should appear from this patch. The test
could as well segfault or anything else, it's a bit of a gamble.

This bug will be fixed along with the expectation in a subsequent patch.

Change-Id: Ie2da77c642a84cafc0f528985930697ec167183b
1 file changed