none OS specific i386 setjmp

[Doug Evans]

   Date: Thu, 9 Oct 1997 15:59:24 -0500 (CDT)
   From: Joel Sherrill <joel@OARcorp.com>

   On Thu, 9 Oct 1997, Doug Evans wrote:

   > Thanks.  i386/setjmp.S is in our source tree but it didn't make it into
   > 1.8.0.  I'll fix that.

   There was also a sys subdirectory with the matchine setjmp.h. :)

I know of cygwin32, go32, and sysvi386.  I fixed configure.in
to not set machine_dir for those.