Make configpm produce better diagnostics for malformed glossary entries

Make configpm produce better diagnostics for malformed glossary entries

Patch 8b6a017ccef7126ae5bcac137fa9a45de4f2c155 added some malformed
entries to Porting/Glossary. (The entries were missing a trailing
colon).

These malformed entries would produce a cryptic one-line warning,
but only when various files were being regenerated. To make things
more difficult these warnings would be produced at the top of, or
in the middle of a large stream of other compilation actions, easily
allowing one to overlook them. Even if you noticed them the information
provided did not make it particularly easy to figure out what was wrong.

This patch changes things so that the warnings contain more information,
it also causes configpm to die, and thus break the build process, once
it finishes scanning the glossary if there were any warnings during
processing. This allows us to avoid whackamole when dealing with multiple
broken entries, and makes it painfully obvious if there are issues
processing the glossary file, which should prevent any future repeat
of the errors in 8b6a017ccef7126.