Remove special case for allowing override on Qt 4 for windows.

Apparently I was a bit optimistic about Visual Studio 2010's
override keyword standard compliance. It doesn't allow use
on destructors when C++11 override does. Just remove it for
non Qt5 builds.
log-users: add button, dump to stdout, badly
log-users: add icon
log-users: log to (same) file every 30 seconds
log-users: log to filename with timestamp
log-users: print user counts, change prefixes
log-users: write to ~/Documents/mumble-user-logs/
log-users: write files in binary mode with \r\n