[buteo-syncml] tests: Fix execution w/o -devel subpkg

The library symlink with no version suffix only comes with the -devel
subpkg and so the test fails on resolving the library symbol when the
-devel subpkg is not installed.

Removing of "lib" prefix and ".so" suffix is not necessary but it is the
preferred usage so fixing all in one go.
Merge pull request #11 from martyone/fix-tests

tests: Fix execution w/o -devel subpkg