to ensure that macros tested with #if/#ifdef
are defined properly before they are tested.

This is a partial application of a patch from pkts.ca
for issue 80; the other parts of that patch conflict
with a patch from Akim Demaille <demaille@gostai.com>
which was committed in revision 715
<http://code.google.com/p/distcc/source/detail?r=715>.

to do a better job of error checking.

        * src/hosts.c (strndup): Use the standard signature (without
        static), so that we don't conflict with GCC's builtin signature.
        Now that it is not static, declare it, to avoid warnings.

Optional GSS-API Functionality.

This patch implements mutual authentication, out of sequence and
replay detection using the GSS-API.  The changes implemented are
optional and are turned off by default.

This option is specified to the client through an environment variable
as is the name of the server principal to authenticate.  Currently
the server principal can be left unspecified and a default based on
the host keytab will be used.

This option is specified to the daemon through a command line option,
with the name of the principal whose credentials the daemon should
use specified as an environment variable.  A simple handshake is
exchanged between the client and server in order to prevent
unecessary delays and protocol derailments when mixing authenticating
and non-authenticating clients and servers.

Revised based on review comments.
GSS-API authentication is now implemented as a per host option.

Revised further by me (Fergus Henderson) to fix a spelling error
and to rename the per host option from ",gssapi" to ",auth".

* Still needs configure flag masking for IPv6 literals
* Needs some fix for zeroconf hosts that have both and IPv6 and IPv4 address

but not ",lzo".

Previously, setting ",cpp" without ",lzo" would quietly set the protocol
version to -1, which the server would then quietly reject (logging as
"REJ_BAD_REQ"), and then the client would guess (poorly) at why the
server had dropped the connection.

Reviewed by Craig Silverstein.

(typically the only change is in the FSF street address).  Add Google
copyright line in some places it was missing.  Add GPLv2 notice to
avahi patches.

OKed by fergus

Also, fix the emacs var-setting line: it was missing a semicolon
before, which means the entire line was being ignored.

No contentful change.

Reviewed by fergus@google.com

lines.  Fixed up resulting mis-indented code I noticed (mostly in
files that used 8 space indents, or used 4-space and 8-space indents
in the same file (!)).  Added the emacs tab-var setting for all files,
not just some of them.

I also added in copyright notices for files I noticed that didn't have
them.  We'll want to do another pass-through to fix these up properly,
though.

I used the following perl snippet to check for mis-indented code after
converting tabs to whitespace:

  $ for i in *.{c,h}; do echo $i; perl -nle 'if ($indent > 0) {$sp=" " x $indent; /^$sp[^ ]/ && print "$.: $_"; $indent=0;}; if (/^( *).*{/ ) {$indent=length($1);} else {$indent=0;}' $i; done | less

It had false positives, but hopefully didn't miss anything.

Reviewed by klarlund@google.com