fix for resetting a menu item label to its original value in a guard. Refs: #70.
This fix removes an optimization in HostMenus.PrepareMenu:
The menu item label was updated only if it differed from its standard value.
Resetting a changed label to its original value is thereby not
detected correctly as a change.
Fix as proposed by Gerard Meunier in CPC 1.7 rc5.

Signed-off-by: Josef Templ <josef.templ@gmail.com>