fixed configure.in when zarith is installed in subdirectory zarith
fixed configure.in when zarith is installed in subdirectory zarith

douglas-larocca/why3,jpdeplaix/why3,douglas-larocca/why3,jpdeplaix/why3,douglas-larocca/why3,ssaavedra/why3,ssaavedra/why3,ssaavedra/why3,jpdeplaix/why3