Change sigTTOU/TTIN to IGNORE by default

[Simon Marlow]

> My local copy of ghc-4.08.1 likes to stop a program when running it
> with "&" (nohup) by default, I have to call
>   Posix.installHandler Posix.sigTTOU Posix.Ignore Nothing
> first to get the desired behaviour. However, my local copy of
> Stevens´ "UNIX Network Programming" says:
> 
> "SIGTTOU: [..] By default a background process is allowed to write to
> its control terminal, but you can specify that a background 
> write is to
> generate this signal instead."
> 
> In other words: Unless I´m setting setting this signalhandler 
> myself to
> block me and didn´t notice it or ghc is plainly wrong.
> 
> In the latter case SIGTTIN should be changed, too.

I couldn't reproduce this problem: just ran "hello world" in the
background, it printed the message and exited.  Could you give more
details?

Cheers,
	Simon