During development in a feature tree, when adding
one function which took a "const CHARSET_INFO *" parameter and passed
it to String::set_charset(), it appears that String::set_charset()
has only a CHARSET_INFO* parameter, causing a compilation problem.
In the present patch, we change String::set_charset() to accept
"const CHARSET_INFO*" instead.
Thus String::charset() has to return this type too. As the return
value of String::charset() is used as parameter in calls to constructors
of Field descendants, those constructors have to accept
"const CHARSET_INFO*" instead of CHARSET_INFO*. The patch fixes all
those "dependencies". After it, "const CHARSET_INFO*" is more frequent
in code than "CHARSET_INFO*", which is normal as most code needn't
update the content of any CHARSET_INFO structure. This now gives the
charset-managing code guarantees that users of charsets won't change
their content.
Copyrights are updated to match recommendations:
last year = 2011; Oracle; but also (c) (not (C)), and the correct
FSF address (Franklin Street, and FSF has "Inc.").