Define colours for all wxSYS_COLOUR_XXX values in wxUniv.

Define colours for all wxSYS_COLOUR_XXX values in wxUniv.

Ensure that we have enough elements in the array used by
wxSystemSettings::GetColour() in wxUniv to avoid the assert which happened
when e.g. wxSYS_COLOUR_LISTBOXTEXT was requested from it. This resulted in
an infinite stream of asserts and a crash when trying to use wxTreeCtrl in
wxUniv.

Closes #11702.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@65055 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775