Use wide-character library routines, if available, for upper/lower/initcap

functions.  This allows these functions to work correctly with Unicode and
other multibyte encodings.  Per prior discussion.

Also, revert my earlier change to move installation path mashing from
Makefile.global to configure.  Turns out not to work well because configure
script is working with unexpanded variables, and so fails to match in
cases where it should match.