x11/gbsddialog: add new port

[khorben]

gbsddialog is an implementation of bsddialog, a text-based user interface to be used in scripts and tools, such as in the official FreeBSD installer, bsdinstall(8). gbsddialog uses Gtk+ dialogs and widgets instead of console-based equivalents. The objective is to reproduce the same behaviour as the original tool, respecting the exact command-line parameters and output. gbsddialog can then be used as a drop-in replacement to bsddialog, effectively granting the possibility to install and configure FreeBSD entirely in graphical mode.

In addition, an implementation of Xdialog is also provided, for use with bsdconfig(8) when invoked in graphical mode with -S or -X.

Sponsored by: The FreeBSD Foundation