net/wpa_gui: Several improvements

• Adds DEBUG option to simplify troubleshooting
• Adds debug logging of wpa_supplicant control interface
• Installs the manpage
• Adds USE_QT4=corelib
• Makes wpa_gui executable setuid to allow it to easily connect to wpa_supplicant control socket
• Fixes the problem that wpa_gui sometimes picks up .pid file instead of the control interface

PR: 211214
Submitted by: Yuri Victorovich <yuri@rawbw.com>
Reviewed by: koobs