Unbreak Android build: set VERSION/SOVERSION on Android, needed for cmake config

Summary:
With commit faecf23d setting those
properties was disabled. The new cnake config file creation now requires
these properties though, the build fails otherwise.
It is not obvious why those properties should not be set on Android,
with them set the build works fine, the apk installs and Marble Maps
works for me.

Reviewers: sanjibanb, nienhueser, #marble

Reviewed By: nienhueser, #marble

Differential Revision: https://phabricator.kde.org/D2430