Added framework to create/drop and manager buffers for multiple key caches


include/my_getopt.h:
  Fixed prototype
include/my_sys.h:
  Added (temporary) KEY_CACHE type
include/mysqld_error.h:
  New error messages
mysql-test/r/select_safe.result:
  Updated test results
mysql-test/r/variables.result:
  Updated test results
mysys/my_getopt.c:
  Fixed bugs with GET_ASK_ADDR
sql/Makefile.am:
  Make sql_yacc.o depend on all header files in sql directory
sql/item_func.cc:
  Added support for variable components
sql/mysql_priv.h:
  Added support for variable components
sql/mysqld.cc:
  Added support for multiple key caches
sql/set_var.cc:
  Added support for multiple key caches
sql/set_var.h:
  Added support for multiple key caches
sql/share/czech/errmsg.txt:
  New error messages
sql/share/danish/errmsg.txt:
  New error messages
sql/share/dutch/errmsg.txt:
  New error messages
sql/share/english/errmsg.txt:
  New error messages
sql/share/estonian/errmsg.txt:
  New error messages
sql/share/french/errmsg.txt:
  New error messages
sql/share/german/errmsg.txt:
  New error messages
sql/share/greek/errmsg.txt:
  New error messages
sql/share/hungarian/errmsg.txt:
  New error messages
sql/share/italian/errmsg.txt:
  New error messages
sql/share/japanese/errmsg.txt:
  New error messages
sql/share/korean/errmsg.txt:
  New error messages
sql/share/norwegian-ny/errmsg.txt:
  New error messages
sql/share/norwegian/errmsg.txt:
  New error messages
sql/share/polish/errmsg.txt:
  New error messages
sql/share/portuguese/errmsg.txt:
  New error messages
sql/share/romanian/errmsg.txt:
  New error messages
sql/share/russian/errmsg.txt:
  New error messages
sql/share/serbian/errmsg.txt:
  New error messages
sql/share/slovak/errmsg.txt:
  New error messages
sql/share/spanish/errmsg.txt:
  New error messages
sql/share/swedish/errmsg.txt:
  New error messages
sql/share/ukrainian/errmsg.txt:
  New error messages
sql/sql_lex.cc:
  Fixes for quoting of variables.
sql/sql_parse.cc:
  Fix after changing prototype for get_system_var
sql/sql_show.cc:
  Fix after introducing variable components
sql/sql_yacc.yy:
  Support for variables with components (To support multiple key caches)