- removed LINUX_DIST as string (can't do string ops in preprocessor)
- added XXX_LINUX disabling flags in wtest in order to be able to disabled
  wolfilter tests based on the linux distribution (TODO: Fedora/RHEL split
  and LINUX_DIST_REV_MAJOR and LINUX_DIST_REV_MINO instead of LINUX_REV)
- disabled mylang wolfilter tests for openSUSE (as they fail consistently on
  the OBS cluster but never in a real openSuse)