Check logging verbosity before evaluating format parameters

Vast majority of diagnostic logging from mce is not emitted to journal
on default verbosity. Spending cpu time evaluating format parameters
and pushing them to stack just to be discarded makes no sense.

Now verbosity level is checked 1st and potentially time consuming
parameter evaluation is done only if the message is going to be
emitted to the journal.

[mce] Check logging verbosity before evaluating format parameters. Fixes JB#22310
Fix various issues in mce-log.h

Reserved symbol names (__xxx, _XXX_, etc) were replaced with XXX_.

Added missing dummy counterparts for real functions and removed
useless and repetitive doxygen documentation of all dummies.

Indented #if blocks to make nesting level more visible.

Split long lines.
Merge pull request #210 from spiiroin/check_verbosity_1st

Check logging verbosity before evaluating format parameters