"prefs.capture_real_time", not "prefs.capture_auto_scroll", should

"prefs.capture_real_time", not "prefs.capture_auto_scroll", should
control whether we have a child process do the capturing; a user might
want the packet list to be updated as packets arrive but *not* want it
to scroll so that the most recently arrived packets are shown.

"prefs.capture_auto_scroll", not "auto_scroll_live", should control
whether we scroll a real-time-update capture's packet list;
"auto_scroll_live" isn't set by the capture dialog box,
"prefs_capture_auto_scroll" is.

git-svn-id: http://anonsvn.wireshark.org/wireshark/trunk@3388 f5534014-38df-0310-8fa8-9805f1628bb7