AbstractCompileMojo: fix versioned flag

The negation was factored into the expression in
54b56435a18668f17cec76c52464d1eec74980fb, but the && was not replaced
with ||, so the refactoring changed the evaluation of the expression.

This change restores it back to the prior meaning, but with the
negations factored in as desired.

Fixes GitHub issue #25.
AbstractCompileMojo: clean up whitespace