Cleanup handling of optional dependencies

Cleanup handling of optional dependencies

Don't use super pedantic parsing of the argument and work with the
generated variable instead of assigning it to our own and set it
to "check" if not value is assigned. Then search for a dependency
if the with variable is anything other than "no" and fail if it
was set to "yes".

In addition, the WITHOUT_xxx defines are replaced with WITH_xxx defines.

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>