bug#33218: Updated dfa.c: unused function charclass_context

[Paul Eggert]

Bug#33218 dated 2018-10-31 seems to have been fixed by Jim Meyering in Gnulib 
commit 95cd86dd7aa4425037b9c710f88fd59e38601ff1 (2018-12-15 18:09:35 UTC) and 
then fixed in a different way since then, so I'm closing this old bug report.