[PATCH, doc] PR30739: awk is a build prerequisite

[Andrew Pinski]

Ok I found the old emails about what version of GNU awk caused the
issues, it was 3.1.2.
See the thread starting at
http://gcc.gnu.org/ml/gcc-patches/2003-06/msg01894.html .
It was released part of a cygwin release.

Thanks,
Andrew Pinski