[distcc] More on distcc in disguise

[Wayne Davison]

I'm just fiddling with some of the additional features we talked about
in the earlier discussion.  I haven't tried to write this cleanly yet,
but I did make the following changes:

 - The our-name-matching logic looks for a "distcc" prefix instead of
   requiring an exact match.

 - The "safeguard" environment twiddling/checking has been extended to
   allow a current level of "1" as long as we are in disguise and we
   successfully twiddled the path.  This also forces a local compile.
   This allows distccd to have a disguised distcc on the path and still
   have the compile succeed (as long as the distcc can hand it off down
   the path).

 - It contains some of the CVS code to use putenv() instead of setenv().

The new patch is still for version 1.1 (since I'm not using the CVS
version while the scheduler is still in flux):

    http://www.clari.net/~wayne/wrapper-plus.patch

I've tested that it properly fails when there are two disguised distcc
dirs on distccd's path (simulating a loop) and succeeds if there is only
one.  Note also that the patch has several debug log messages about the
current safeguard level -- I think these should be reduced in the final
version, though.

..wayne..