After the kdelibs update to 4.11.30 the CMake policies used by kdelibs-based
projects got stricter.
- Fix `make configure'. The upstream git repository has a add_subdirectory(doc)
call, but the code generating the release tarball also added a
macro_optional_add_subdirectory(doc) call that was causing CMake to error out
due to the same directory being added twice to the build system.
- Fix `make build' with the MUSEPACK option. The FindMuse.cmake patch from
r346999 was hardcoding MUSE_LIBRARIES the wrong way. The find_library() call
should have been kept, otherwise the linker is passed "-lmpcdec" instead of
"/full/path/to/libmpcdec.so".
734d437047