#1 Improve const-correctness

[Markus Elfring]

Would you like to apply the advices from the article "http://en.wikipedia.org/wiki/Const-correctness" to more places in your sources?
I suggest to add the key word "const" to the type specifiers for parameters like the following.
- http://mstone.svn.sourceforge.net/viewvc/mstone/trunk/mstone/src/bench.h?revision=10&view=markup
host, protocol (function "resolve_addrs")

- http://mstone.svn.sourceforge.net/viewvc/mstone/trunk/mstone/src/generate.c?revision=7&view=markup
GEN_HDRS, GEN_HDRFORMAT, EOM, MIME_SEPARATOR, ... (global "variables")