Force restoration of GS before signal handlers but only if
the libc uses signal wrappers and GS != 0.
Also restore flags/fs/gs after a vm86 call to work around a bug
in 2.4 kernels.
The implementation is hackish -- any beautification improvements
are welcome, but it seems to work.


git-svn-id: https://dosemu.svn.sourceforge.net/svnroot/dosemu/trunk@664 7758b857-130e-0410-ab9c-d8735a528d18