Since grep's DFA matcher is now being used by two gnulib-enabled
projects, grep and sed, it makes sense to version-control its
sources and unit tests in one place: here.
* modules/dfa: New module.
* modules/dfa-tests: New file.
* lib/dfa.c: New file, from grep.
* lib/dfa.h: Likewise.
* lib/localeinfo.c: Likewise.
* lib/localeinfo.h: Likewise.
* tests/dfa-match-aux.c: Likewise.
* tests/dfa-invalid-char-class.sh: Likewise.
* tests/dfa-match.sh: Likewise, with minor changes.
* MODULES.html.sh (Misc): Add "dfa" to this list.