No changes, just move wxComboBox::Clear() out of line in wxGTK.

Make this function non-inline to facilitate further modifications.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@78084 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Fix clearing wxCB_READONLY wxComboBox in wxGTK.

wxComboBox::Clear() must call wxTextEntry::SetValue() explicitly instead of
calling its Clear() which just forwards back to wxComboBox own SetValue(),
which (correctly) doesn't work for read-only comboboxes when passed an empty
string.

Closes #16654.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@78085 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Restore code for closing inherited file descriptors under non-OS X.

The code for doing this was accidentally disabled in r74957, which intended to
disable it for Darwin, but ended up disabling it for everything but Darwin.

Reenable it for all platforms now, clearly it didn't hurt to have it enabled
under Darwin, and we do need to do it, e.g. see #12636.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@78086 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775