symdef.pas:
  * tprocdef.defaultmangledname: add some kind of differentiator to the result def, so that x(integer;integer) and x(integer):integer generate different mangled names
  * make_mangledname: also use the returndef instead of a potentially uninitialized variable like was done for tprocdef.defaultmangledname and also add a prefix (so that the two are compatible)

+ added test

git-svn-id: trunk@29579 -