The goal is to shuffle things around allowing us to use this variable in
the packing lists. This should reduce a little bit of churn going
forward given some files get bumped with every point release.
For example in Python 3.9 we make the following update:
-lib/python3.9/lib2to3/Grammar3.9.10.final.0.pickle
+lib/python3.9/lib2to3/Grammar${FULL_VERSION}.final.0.pickle
-lib/python3.9/lib2to3/PatternGrammar3.9.10.final.0.pickle
+lib/python3.9/lib2to3/PatternGrammar${FULL_VERSION}.final.0.pickle
ok kmos@ (MAINTAINER), sthen@