These appear not to have any effect any more. They were initially used
to conditionally compile and link some files with replacements for
standard library functions, but seem not to have been used after r828
("Moved to nbase system for compatability funcs").
If you have trouble updating after this revision you need to follow
these instructions. You have probably just seen an error like this:
svn: URL 'svn://svn.insecure.org/nping' of existing directory 'nping'
does not match expected URL 'svn://svn.insecure.org/nmap/nping'
This is caused by the replacement of SVN externals.
Here's what you need to do. First, save any local changes you might have
in the nping, nsock, nbase, ncat, and zenmap directories. (For example
by running "cd nping; svn diff > ../nping.diff".) If you don't have any
local changes you can skip this step.
Then run these commands:
rm -rf nping/ nsock/ nbase/ ncat/ zenmap/
svn update
svn cleanup
If all else fails, you can just delete your whole working directory and
check out anew:
svn co --username guest --password "" svn://svn.insecure.org/nmap
There may be further discussion in the mailing list thread at
http://seclists.org/nmap-dev/2011/q4/303.
