Fixing grep -D skip

[David Xu]

I am trying to fix a bug in GNU grep, the bug is if you
want to skip FIFO file, it will not work, for example:

grep -D skip aaa .

it will be stucked on a FIFO file.

Here is the patch:
http://people.freebsd.org/~davidxu/patch/grep.c.diff2

Is it fine to be committed ?

Regards,
David Xu