Support _U (local deleted, remote modified) and
UT (file type changed in conflict) modes.

Note that 'file type changed' does not refer to
changes in the executable bit, instead it denotes
replacing a file with a link, or vice versa.
Signed-off-by: NAlexander Gavrilov <angavrilov@gmail.com>
Signed-off-by: NShawn O. Pearce <spearce@spearce.org>