#1 Improve "const correctness"

[Markus Elfring]

Would you like to apply the advices from the article
"http://en.wikipedia.org/wiki/Const_correctness" to
your sources?
I suggest to add the key word "const" to the type
specifiers for parameters like the following examples.

http://cvs.sourceforge.net/viewcvs.py/cfgsh/cfgsh/cfgsh.c?rev=1.4&view=markup
1. tmp_file, file (function "commit_file")
2. text (function "word_num")
3. host_name (function "resolve")
4. if_name (functions "get_if_flags", "set_if_flags")