Fix CMake >= 3.2 problems with soname
Fix CMake >= 3.2 problems with soname

When compiling QCA:

   fatal error: -soname: must take a non-empty argument

Solution from:
http://stackoverflow.com/a/32399514/2319028

opengisch/OSGeo4A,opengisch/OSGeo4A,opengisch/OSGeo4A