mysql-client used static buffer to concatenate server-
version and version_comment. Sufficiently long comments
could get cut off. This was harmless, but looked daft.

Now using a dynamic buffer instead.

client/mysql.cc:
  Use dynamic rather than static buffer for server
  information. If we can get both version and comment,
  concat them and use that. Otherwise, try to use just
  version. If that fails too, return empty string so
  overly trusting callers do not crash. Release memory
  as needed.