logger: Bring back ability to turn debug on by source file

Somewhere along the way we lost the ability to debug individual
source files.  For modules, this wasn't a big deal but all the
source files in ./main are in the one "core" module so debugging
individual core capabilities was almost impossible.

* Added a test to DEBUG_ATLEAST that also checks __FILE__ instead
of just module name.  Any source file will work even if it's in
a module subdirectory.

Change-Id: Icc0af41837f3b1679dec7af21fa32cd1f7469f6e