cfengine: use opt_prefix for pcre
CurlDownloadStrategy no longer uses `?` in downloaded filenames

Strip `?` and trailing characters from URL extensions and basenames.

This makes some install methods cleaner, and prevents staging of files
with `?` in the name, as that is a weird character.

Affects 2 formulae in core (though potentially externals will need to be fixed.)
Use ScriptFileFormula

Switch these to use ScriptFileFormula, since they no longer
need to munge the installed filenames.
miniupnpc 1.8.20130503