mergetool: Fix typo in options passed to kdiff3

Fix missing double hyphens in "-L1" and "-L2"
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

git-mergetool.sh

@@ -192,10 +192,10 @@ merge_file () {
     case "$merge_tool" in
 	kdiff3)
 	    if base_present ; then
-		(kdiff3 --auto --L1 "$path (Base)" -L2 "$path (Local)" --L3 "$path (Remote)" \
+		(kdiff3 --auto --L1 "$path (Base)" --L2 "$path (Local)" --L3 "$path (Remote)" \
 		    -o "$path" -- "$BASE" "$LOCAL" "$REMOTE" > /dev/null 2>&1)
 	    else
-		(kdiff3 --auto -L1 "$path (Local)" --L2 "$path (Remote)" \
+		(kdiff3 --auto --L1 "$path (Local)" --L2 "$path (Remote)" \
 		    -o "$path" -- "$LOCAL" "$REMOTE" > /dev/null 2>&1)
 	    fi
 	    status=$?