On Windows with certain keyboard layout combinations you can get a
benign terminal warning like this:
Could not open registry key 'SYSTEM\CurrentControlSet\Control\Keyboard
Layouts\D0010413'
When using a lot of plug-ins, like GIMP does, this warning can show up
a lot of times.
The code after this warning, still has another last check, that, when it
fails, will show a warning.
We change the first g_warning to a g_debug statement, to reduce the
amount of warning messages.
Closes#5109
99a816c361