Fix infinite prompt loop on stdin EOF

[arcnmx]

^D now exits the shell as it should.

Pull Request checklist

Note: these are not necessarily requirements

• I reformatted the code with clang-format
• I checked to make sure my submission worked
• I am the author of submission or have permission from the original author
• Requires update of the PS2SDK or other dependencies
• Others (please specify below)

Pull Request description

Fixes the following issue:

pfsshell < /dev/null
> > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >

Which also occurs if one uses ctrl+d in the prompt in an attempt to exit the shell.

[uyjulian]

Thanks!