git-gui: Use -M and -C when running blame.

Since we run blame incrementally in the background we might as well get
as much data as we can from the file.  Adding -M and -C definately makes
it take longer to compute the revision annotations, but since they are
streamed in and updated as they are discovered we'll get recent data
almost immediately anyway.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

git-gui.sh

@@ -3276,7 +3276,9 @@ proc read_blame_catfile {fd w commit path texts w_lno w_file} {
 	if {[eof $fd]} {
 		close $fd
 		set blame_status($w) {Loading annotations...}
-		set fd [open "| git blame --incremental $commit -- $path" r]
+		set cmd [list git blame -M -C --incremental]
+		lappend cmd $commit -- $path
+		set fd [open "| $cmd" r]
 		fconfigure $fd -blocking 0 -translation lf -encoding binary
 		fileevent $fd readable "read_blame_incremental $fd $w $texts"
 	}