Use Coccinelle's "depends on" directive to exclude files from certain
transformations. This should make them a bit simpler and possibly
faster, since we don't have to shell out to Python.
Unfortunately, this works only for file/directory exclusions. For
function and other more complex exclusions we still need to use Python,
at least for now.
Also, completely drop the file exclusion for man/ in the xsprintf
transformation, since we filter out everything under man/ before we even
run Coccinelle (in run-coccinelle.sh).