Use of absolute paths in some generated CMake files

[agarny]

libCombine shows the same issue as the one described in NuML/NuML#24. In addition, I found that if I pass a target for the zipper library then in Combine-static-config-release.cmake, IMPORTED_LINK_INTERFACE_LIBRARIES_RELEASE shows /some/absolute/path/my_zipper_target rather than simply my_zipper_target, but that might be something that I have done wrong... although it works fine for zlib (i.e. I see my_zlib_target and not /some/absolute/path/my_zlib_target). I haven't checked, but could it be that LIBZ_LIBRARY and ZIPPER_LIBRARY are handled differently?

[agarny]

I take it back when it comes to my_zlib_target. I have the same problem as with my_zipper_target and (I believe that) it's my problem, not that of libCombine.