a2737333 commit introduced a possibility to build libselinux without
rpm_execcon() when DISABLE_RPM is set. However, it didn't cover SWIG
bindings. With this commit the rpm_execcon() bindings are not created.
Fixes:
ImportError: /usr/lib64/python3.5/site-packages/selinux/_selinux.so: undefined symbol: rpm_execcon
Signed-off-by: Petr Lautrbach <plautrba@redhat.com>