#977 Prepared statements in embedded library


include/mysql.h:
  read_prepare_result function moved to 'virtual'
libmysql/client_settings.h:
  declare proper function for libmysql
libmysql/libmysql.c:
  some code moved from implementation of read_prepare_result to 
  mysql_prepare_result to make creating separate (remote and embedded-server)
  versions easier
libmysqld/libmysqld.c:
  emb_read_prepare_result prototype
sql-common/client.c:
  cli_read_prepare_result added to the client_methods
sql/client_settings.h:
  we don't need prepared statements in mini_client
sql/sql_prepare.cc:
  embedded send_prep_stmt added