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.)
Since this is completely different then what is in the GIT source, is it what we should go with? My biggest concern is "makeimage" versus "linuxdeploy" and simplistically. This one has the advantage of adding the Manual documentation.
But it is easy enough to add the Manual documentation AND this patch to the current GIT one:
0003-Add-CONFIG_OPTIONS-env.-variable-handling-to-bld_app.patch
Git patch was (hopefully) just this - diff between what we have there in root of cinelerra-5.1 tree (there is another script in blds/ directory! but with same name. they are different!) and my changes.
If you want to mod script in blds with same $CONFIG_OPTIONS handling - go ahead, you have linuxdeploy working at least on slightly older OSes. (we ab/use appimage as some way to fossilize current build so we can easily retest even if os libs all slip away. Idea behind appimages was building on oldest possible OS of course)