external/librevenge,libmwaw,libodfgen,libwps: fix self-linked symlinks build problem

...LibreOfficeDev.app/Contents/MacOS/librevenge-0.0.0.dylib: Too many levels of symbolic links
(librevenge-0.0.0.dylib --> librevenge-0.0.0.dylib: broken symbolic link to librevenge-0.0.0.dylib)

The reason for this is that symlink librevenge-0.0.dylib
(UnpackedTarball/librevenge/src/lib/.libs/librevenge-0.0.dylib -> librevenge-0.0.0.dylib)
is copied via cp --no-dereference, thus becoming linked to self.

Change-Id: I4b918c35c594800fb2d7f84ee0ee9f2ff2a5fe14
Reviewed-on: https://gerrit.libreoffice.org/9783
Tested-by: David Tardon <dtardon@redhat.com>
Reviewed-by: David Tardon <dtardon@redhat.com>