show bug in logging: out-of-bounds check should end with user categories

In the background osmo_log_info array, the user's logging categories are
enhanced by the library internal ones. So far logging category range checking
only checked for the larger array bounds, although passing a logging category
>= num_cat_user is already semantically unknown and should redirect to
DLGLOBAL.

Add a check to logging_test.c to show that this isn't happening. Instead of
DLGLOBAL, a logging category that happens to be at that index is queried.

The bug is confirmed by logging_test.err only showing "(e)" and not "(d)":
"(e)" is shown because the first category after the user ones happens to be
DLGLOBAL. "(d)" is omitted since it hits a category that's not on debug level.

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

Change-Id: I397278714018ee9a0ae5101515f31ddddf79c2ec
2 files changed