Upgrade to openbsd's netcat.

Upgrade to openbsd's version of netcat, available for download
from http://www.openbsd.org/cgi-bin/cvsweb/src/usr.bin/nc/

This version has been modified to remove BSD specific calls
and other functionality unnecessary for Android. The removed
portions of code are surrounded by #ifdef ANDROID / #endif.

This code corresponds to the following openbsd versions:

  atomicio.c: v1.10
  atomicio.h: v1.2
  netcat.c:   v1.103

The file socks.c and nc.1 are not included in this change.

Change-Id: I39df7fbe335af97e092dd4d4a96f957d6d1a5b5d
36 files changed