gitk: Highlight only when search type is "containing:".

When the search type is "touching paths" or "adding/removing string",
it's not very useful to highlight instances of the search string in
the commit message, headline or author name, so this disables the
highlighting in those cases.

This was suggested by Mark Burton <markb@ordern.com>, but the
implementation is different to his patch, which tested $gdttype at
each place where $markingmatches was tested.
Signed-off-by: NPaul Mackerras <paulus@samba.org>

gitk

@@ -4121,7 +4121,7 @@ proc askvhighlight {row id} {
 
 proc hfiles_change {} {
     global highlight_files filehighlight fhighlights fh_serial
-    global highlight_paths gdttype
+    global highlight_paths
 
     if {[info exists filehighlight]} {
 	# delete previous highlights
@@ -6286,10 +6286,11 @@ proc findmore {} {
 proc findselectline {l} {
     global findloc commentend ctext findcurline markingmatches gdttype
 
-    set markingmatches 1
+    set markingmatches [expr {$gdttype eq [mc "containing:"]}]
     set findcurline $l
     selectline $l 1
-    if {$findloc == [mc "All fields"] || $findloc == [mc "Comments"]} {
+    if {$markingmatches &&
+	($findloc eq [mc "All fields"] || $findloc eq [mc "Comments"])} {
 	# highlight the matches in the comments
 	set f [$ctext get 1.0 $commentend]
 	set matches [findmatches $f]