PR11334: support for very-basic regex match operator in script

PR11334: support for very-basic regex match operator in script

* session.h (systemtap_session::dfas, systemtap_session::dfa_counter): new fields.
* session.cxx (systemtap_session::systemtap_session): correctly initialize dfa_counter in constructors.
* re2c-migrate/regcomp.h (class stapdfa): remove dummy stapdfa() constructor.
(emit_matchop): remove function.
(emit_matchop_start, emit_matchop_end): new function.
(regex_to_stapdfa): mistake fixes.
* re2c-migrate/regcomp.cxx (class stapdfa): ditto.
(emit_matchop): remove function.
(emit_matchop_start, emit_matchop_end): new function.
(regex_to_stapdfa): mistake fixes.
* re2c-migrate/actions.cc (Scanner::getRange): get rid of warnings.
* elaborate.cxx (class regex_collecting_visitor): new visitor to populate dfas.
(gen_dfa_table): new function.
(semantic_pass): add call to gen_dfa_table().
* translate.cxx (c_unparser::visit_regex_query): add actual match invocation.
(translate_pass): generate regex matching functions.
* Makefile.am, Makefile.in: add regcomp stuff to main stap compilation.
* re2c-migrate/translate.cc moved to re2c-migrate/regtranslate.cc
  (to avoid Makefile naming conflict).
* re2c-migrate/Makefile.am, re2c-migrate/Makefile.in: update for regtranslate renaming.