The documentation stated that (a) wxSYS_CARET_{ON|OFF}_MSEC settings
were not supported on MSW and (b) if a setting was not supported a
negative value was returned. However, when calling
wxSystemSettings::GetMetric(wxSYS_CARET_{ON|OFF}_MSEC), not only the
method asserted but 0 was returned instead of a negative value.
Fix this by using the value returned by ::GetCaretBlinkTime() for
wxSYS_CARET_{ON|OFF}_MSEC.
The documentation for wxSYS_CARET_TIMEOUT_MSEC does not list any
platform limitations; however, attempting to obtain this value resulted
in an assert and 0 returned. Fix this by returning -1. Returning -1 may
not the be the ideal solution, but there is no value reserved for the
setting not being supported and the caret on MSW usually blinks.
Closes https://github.com/wxWidgets/wxWidgets/pull/1285
e5d850d76c