int33() now uses a callback into the mouse driver to make sure the
hogthreshold is done after the call even for DOS mouse drivers.
A DOS mouse driver can now redirect int33; in that case we use NOREVECT
for mouse_int(). To combine this with the callback via the hog code (which
is always revectored) some extra checks and function pointer adjustments
have to be made.
Removed the unused indirect function pointer for the mouse callback.
Enabling the internal driver no longer always sets the int33 vector.
Implemented a second mouse callback for the PS/2 mouse BIOS.
All this combined gives a PS/2 mouse bios that actually works so a
DOS mouse driver (such as CTMOUSE 1.9) can be loaded into xdosemu --
although to have it usable one needs to grab the mouse.


git-svn-id: https://dosemu.svn.sourceforge.net/svnroot/dosemu/trunk@790 7758b857-130e-0410-ab9c-d8735a528d18