We use visual studio module definitions for the list of symbols to
export when targetting Windows. Fixes CI failure:
../validate/tools/gst-validate.c:460: undefined reference to `gst_validate_spin_on_fault_signals'
With the addition of the .def file for validate we need to make
sure the check-export script from common gets executed so that the
.def stays up to date.
https://bugzilla.gnome.org/show_bug.cgi?id=774638