[Cin]bld_appimage.sh modded to accept CONFIG_OPTIONS env. variable

Just file, not patch I tested it like CONFIG_OPTIONS="--without-thirdparty" ./bld_appimage.sh and it seems to work (not sure what will happen if you pass both --disable-static-build and --enable-static-build. I moved --enable-static-build to its own line so you hopefully can just harmlessly comment it out.)