Change handling of conditional builds in the spec file

Change handling of conditional builds in the spec file

Change handling of build options from using simple define statements
to using the RPMs bcond_without functionality. bcond_without instead
of bcond_with ensures that the old behaviour is preserved (all
options are still enabled by default). This change allows the
convenient "rpmbuild --without xxx" and is in line with:

http://www.rpm.org/wiki/PackagerDocs/ConditionalBuilds