generate these formulae with "genltl".
* src/tgbatest/ltlcounter/: Remove this directory.
* src/tgbatest/Makefile.am: Adjust.
* src/tgbatest/ltlcounter.test, bench/ltlcounter/run: Use genltl
to generate the formulae.
* bench/ltlcounter/README: Do not mention src/tgbatest/ltlcounter/
anymore.