Split pic_iret() into pic_iret() and pic_iret_dpmi(): the callers know
enough, there's no need to check again. Remove bogus pic_iret() call
for VM86_STI.


git-svn-id: https://dosemu.svn.sourceforge.net/svnroot/dosemu/trunk@1323 7758b857-130e-0410-ab9c-d8735a528d18