Fix error when choosing named exec with plane profile names

Merged Christian Boltz requested to merge cboltz/apparmor:cboltz-named-exec into master

When a user choooses to execute to a named profile (not: named child), make sure to get the profile filename in the correct way to avoid a crash.

Fixes: #314 (closed)

I propose this patch for 2.13..master. (Note: I verified that the bug already exists in 2.13, and that this patch fixes it.)