Statically constructing wxCursors as used for the probe
and tune cursors crashes the qa_eagle_plugin test
instantly.
Fix this by introducing a new class CURSOR_STORE,
which allows to abstract the platform wierdness of wxCursors
and allow the simulator to laziliy init its own cursors
at runtime.
This code isn't properly tested, as these cursors are never
actually used. However, it does allow the eeschema unit test
to run.
Fixes: lp:1781191
* https://bugs.launchpad.net/kicad/+bug/1781191
(cherry picked from commit 6f1c3f5ef8)
John Beard