Incorrect signal handling under SYSV machines

[Loren James Rittle <rittle@comm.mot.com>]

I have used es-0.9-alpha1 for many moon under SunOS 4.1.[34] and DEC
Alpha UNIX V4.0.  [Note: I always have `interrupt' set to Control C
under the terminal driver.]  Whenever I hit Control C, most normal
programs interactively activated under the shell are killed and I get
a fresh command prompt.  If I was in the middle of forming a command
line, it is killed and I get a fresh prompt.  Even if I had typed
nothing, I get a fresh prompt.

I recently recompiled it for SunOS 5.X and HP-UX 10.20 with
gcc-2.7.2.1.  For all architectures (even SunOS 4.1.4), I linked
against the readline package.

Under HP-UX 10.20, when I hit Control C twice at any points during a
session under the es shell, the shell ``terminate[s] on signal 2.''

Under SunOS 5.5.1, the shell only responses to the first
Control C, all later Control Cs appear to be eaten somewhere.

Sorry to be so vague, I'm hoping someone out there knows my problem
without me having to fully debug it.

Thanks,
Loren