gitk: Enable gitk to create tags with messages

Currently, tags created using the "create tag" dialog in gitk are
always lightweight tags, i.e., they don't have any annotation
(message).  This enables the user to specify a message; if they do,
gitk will create an unsigned, annotated tag object.

Signed-off-by: David Dulson <dave@dulson.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

gitk

@@ -8701,6 +8701,11 @@ proc mktag {} {
     ${NS}::label $top.tlab -text [mc "Tag name:"]
     ${NS}::entry $top.tag -width 60
     grid $top.tlab $top.tag -sticky w
+    ${NS}::label $top.op -text [mc "Tag message is optional"]
+    grid $top.op -columnspan 2 -sticky we
+    ${NS}::label $top.mlab -text [mc "Tag message:"]
+    ${NS}::entry $top.msg -width 60
+    grid $top.mlab $top.msg -sticky w
     ${NS}::frame $top.buts
     ${NS}::button $top.buts.gen -text [mc "Create"] -command mktaggo
     ${NS}::button $top.buts.can -text [mc "Cancel"] -command mktagcan
@@ -8718,6 +8723,7 @@ proc domktag {} {
 
     set id [$mktagtop.sha1 get]
     set tag [$mktagtop.tag get]
+    set msg [$mktagtop.msg get]
     if {$tag == {}} {
 	error_popup [mc "No tag name specified"] $mktagtop
 	return 0
@@ -8727,7 +8733,11 @@ proc domktag {} {
 	return 0
     }
     if {[catch {
-	exec git tag $tag $id
+	if {$msg != {}} {
+	    exec git tag -a -m $msg $tag $id
+	} else {
+	    exec git tag $tag $id
+	}
     } err]} {
 	error_popup "[mc "Error creating tag:"] $err" $mktagtop
 	return 0