add dune-common/bin to /usr/local/bin:/usr/bin:/bin:/usr/bin/X11:/usr/games variable (fixes #341)

[[Imported from SVN: r849]]

autogen.sh

@@ -47,6 +47,7 @@ for OPT in "$@"; do
 	    if test -d "$OPT/share/dune-common/am"; then
 	      am_dir="$OPT/share/dune-common/am"
 	    fi
+		PATH=$PATH:$OPT/bin
             ;;
     esac
 done