MFC revisions 268999, 269027, 269351-269352, 269354, 269460, 270283,

MFC revisions 268999, 269027, 269351-269352, 269354, 269460, 270283,
270505, 270954, and 270989:
r268999: Add new bsdconfig example scripts; remove obsolete ones
r269027: Update bsdconfig dot module; fixes and enhancements
r269351: Add setvar() for non-FreeBSD platforms using bash as /bin/sh
r269352: Fix syntax error when run under bash
r269354: Update setvar() function introduced in r269351
r269460: Update f_xdialog_info() in bsdconfig's dialog.subr include
r270283: Add `-A' flag to pkg-install(8) when installing dependencies
r270505: Optimize f_which() to be slightly faster still (common.subr)
r270954: Update f_dialog_init() for safer getopts usage (dialog.subr)
r270989: Fix for previously mentioned r270954

Approved by:	re (gjb)

git-svn-id: svn://svn.freebsd.org/base/stable/10@272230 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f