Only convert to use "ansi prototypes" the functions warned from
compilation with "./autogen.sh --prefix=/usr", on a Linux computer.

  Also, only address "trivial" compiler warning fixes in this commit.

  The new .gitignore is the output of a command like:
% find . -name .gitignore -exec cat {} \; | sort | uniq
and only the toplevel .gitignore file was kept.