Changed handing of priv_host to fix bug in FLUSH PRIVILEGES


libmysqld/lib_sql.cc:
  Changed handing of priv_host to fix bug in FLUSH PRIVILEGES
myisam/mi_rkey.c:
  Fix reference to not initialized memory
sql/sql_acl.cc:
  Changed handing of priv_host to fix bug in FLUSH PRIVILEGES
sql/sql_acl.h:
  Changed handing of priv_host to fix bug in FLUSH PRIVILEGES
sql/sql_class.h:
  Changed handing of priv_host to fix bug in FLUSH PRIVILEGES
sql/sql_parse.cc:
  Changed handing of priv_host to fix bug in FLUSH PRIVILEGES
sql/unireg.h:
  Changed handing of priv_host to fix bug in FLUSH PRIVILEGES