makers/AppImage: LD_LIBRARY_PATH poorly configured in AppRun

[servusdei2018]

Currently, the AppRun configured in generated AppImages is:

flutter_distributor/packages/flutter_app_packager/lib/src/makers/appimage/make_appimage_config.dart

Lines 95 to 102 in 0add98c

	String get appRunContent {
	return '''
	#!/bin/bash
	cd "\$(dirname "\$0")"
	export LD_LIBRARY_PATH=usr/lib
	exec ./$appName
	''';

Linux distributions do things pretty differently, but generally libraries are found in usr/lib, usr/lib64, or less commonly, usr/lib32. Therefore, it is very problematic that the default script completely ignores LD_LIBRARY_PATH and overwrites it with a naively assumed directory.

There has been related discussion regarding this in AppImageKit: (AppImage/AppImageKit#126).