On Ubuntu host, build succeeded; but e.g. on Manjaro host, it failed with:
```
./build.sh: line 233: /opt/electrum/contrib/build-linux/appimage/../../../contrib/build-linux/appimage/.cache/appimage/appimagetool: No such file or directory
```
This slightly increases the AppImage size but allows us to be more
compatible with older distributions.
-----
taken from Electron-Cash/Electron-Cash@96644acd6f
It warns about scripts being installed in a location that is not on the
path, but that is inconsequential as they are not used.
-----
taken from Electron-Cash/Electron-Cash@9a29017c5d
When building in docker on macOS, python builds with .exe extension
because the case insensitive file system of macOS leaks into docker.
This causes the build to result in a different output on macOS compared
to Linux. We simply patch sysconfigdata to remove the extension.
Some more info: https://bugs.python.org/issue27631
There are a lot of dupliacted files, testing files and unused libraries
present in the AppImage. Removing these reduces the AppImage size
significantly.
-----
taken from Electron-Cash/Electron-Cash@cff5fb1289
There was a problem where Python would not properly include the faketime
timestamp sometimes. This patch replaces faketime with a patch that is
used by Ubuntu for reproducible builds by exporting BUILD_DATE and
BUILD_TIME with the desired values.
-----
taken from Electron-Cash/Electron-Cash@9532508a3f
We build our own mksquashfs from squashfskit which supports generating
reproducible squashfs images. We use a small wrapper script to remove
the -mkfs-fixed-time which appimagekit passes but squashfskits
mksquashfs does not support.
-----
taken from Electron-Cash/Electron-Cash@dd1f106f4f
see AppImage/AppImageKit#929
SomberNight