logger: Fix linking regression.

Commit 008731b0
caused a regression by resulting in logger.xml
being compiled and linked into the asterisk
binary in lieu of logger.c on certain platforms
if Asterisk was compiled in dev mode.

To fix this, we ensure the file has a unique
name without the extension. Most existing .xml
files have been named differently from any
.c files in the same directory or did not
pose this issue.

channels/pjsip/dialplan_functions.xml does not
pose this issue but is also being renamed
to adhere to this policy.

Resolves: #539