Add installation of libtool-bin for Debian/Ubuntu

While reading the documentation for building Apache Guacamole from source, I saw that there is no instruction for installing libtool-bin.

 If a user follows these instructions, they may encounter this error, at the autoreconf -fi step:

autoreconf -fi
Can't exec "libtoolize": No such file or directory at /usr/share/autoconf/Autom4te/FileUtils.pm line 345, <GEN3> line 6.
autoreconf: failed to run libtoolize: No such file or directory
autoreconf: libtoolize is needed because this package uses Libtool

I would add libtool-bin in the Required Dependencies section so users don't encounter this issue. I intend to open a PR on the documentation.