Switched off Maintainer mode by default as it gave wrong compiler warnings (as it added -Wall after some switches was already turned off)


cmake/maintainer.cmake:
  Add -DFORCE_INIT_OF_VARS to not get warnings generated by -Wall
configure.cmake:
  Don't add -Wall if we already have it. This is to not enable options that are already turned off.
support-files/compiler_warnings.supp:
  Removed suppression that is not needed anymore