gitk: Add a menu option to start git gui
gitk: Add a menu option to start git gui

Git gui already has menu commands to start gitk, and this makes the
relation symmetric.

[19a0ba370c443ba08d20b5061586430ab449ee8c@samba.org - changed "Git Gui" in the menu item to "git gui"]

Signed-off-by: Alexander Gavrilov <75c96f70141fec65a655d202cd4821a09cb99fd1@gmail.com>
Signed-off-by: Paul Mackerras <19a0ba370c443ba08d20b5061586430ab449ee8c@samba.org>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git