Reworded error message about failure to select client to build to say that
none of the clients can be compiled.

See patch #4870


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@25369 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Mark redundant buildings in sdl-clients' worklist view

See patch #4879


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@25372 a0f10bec-cc02-0410-94fc-a9cfff90b4cd