That place is git-revision.c; git-revision.c now lives in lib/log.
Also fix the compilation rules so that all object files that need
micro-revision.i depend on it.
Fun fact: these files used to be called log.[ch] until we ran into
conflicts with systems having a log.h file. But now that we always
include "lib/log/log.h", we should be fine.
The locking code gets its own module, since it's more fundamental
than the higher-level locking code.
Extracting the logging code was the whole point here. :)