Native libraries for armv7l (Raspberry Pi) required to run the software signalcli (https://github.com/AsamK/signal-cli) which is a prequisite for the Signalbot
The signal-cli distribution only contains x86 libraries and the build process for Raspberry is cumbersome, introduces even more dependencies and requires more RAM than a standard Raspberry (so potentially cross compiling)
Libraries will be pulled by the install script automatically from here.