Added api function mysql_get_character_set_info which provides
information about the current client character set.


include/mysql.h:
  Added api function mysql_get_character_set_info which provides
  information about the current client character set.
libmysql/libmysql.c:
  Added api function mysql_get_character_set_info which provides
  information about the current client character set.
libmysql/libmysql.def:
  Added api function mysql_get_character_set_info which provides
  information about the current client character set.
tests/mysql_client_test.c:
  Added api function mysql_get_character_set_info which provides
  information about the current client character set.