Phase 2: Make SPs belong to a DB, and use qualified names.
  As a side effect, using USE in an SP is no longer allowed.
  (It just doesn't work otherwise.)


include/mysqld_error.h:
  New error code (USE is no longer allowed in a stored procedure).
include/sql_state.h:
  New error state (USE is no longer allowed in a stored procedure).
mysql-test/r/sp-error.result:
  Updated result for test of USE in SP (not allowed now).
mysql-test/r/sp-security.result:
  Updated test results for new db column and qualified procedured names.
mysql-test/r/sp.result:
  Updated results for USE in SP (as it's no longer allowed), and
  for new db column in status result.
mysql-test/t/sp-error.test:
  Moved test of USE in SP from sp.test (as it's no longer allowed).
mysql-test/t/sp-security.test:
  Ajusted tests for new db column and qualified procedured names.
mysql-test/t/sp.test:
  Moved test of USE in SP to sp-error.test (as it's no longer allowed).
  Adjusted tests for new db column in status result.
sql/mysql_priv.h:
  mysql_change_db() now has optional arguments for use by SP with qualified names.
sql/share/czech/errmsg.txt:
  New error message: USE is not allowed in a stored procedure.
sql/share/danish/errmsg.txt:
  New error message: USE is not allowed in a stored procedure.
sql/share/dutch/errmsg.txt:
  New error message: USE is not allowed in a stored procedure.
sql/share/english/errmsg.txt:
  New error message: USE is not allowed in a stored procedure.
sql/share/estonian/errmsg.txt:
  New error message: USE is not allowed in a stored procedure.
sql/share/french/errmsg.txt:
  New error message: USE is not allowed in a stored procedure.
sql/share/german/errmsg.txt:
  New error message: USE is not allowed in a stored procedure.
sql/share/greek/errmsg.txt:
  New error message: USE is not allowed in a stored procedure.
sql/share/hungarian/errmsg.txt:
  New error message: USE is not allowed in a stored procedure.
sql/share/italian/errmsg.txt:
  New error message: USE is not allowed in a stored procedure.
sql/share/japanese/errmsg.txt:
  New error message: USE is not allowed in a stored procedure.
sql/share/korean/errmsg.txt:
  New error message: USE is not allowed in a stored procedure.
sql/share/norwegian-ny/errmsg.txt:
  New error message: USE is not allowed in a stored procedure.
sql/share/norwegian/errmsg.txt:
  New error message: USE is not allowed in a stored procedure.
sql/share/polish/errmsg.txt:
  New error message: USE is not allowed in a stored procedure.
sql/share/portuguese/errmsg.txt:
  New error message: USE is not allowed in a stored procedure.
sql/share/romanian/errmsg.txt:
  New error message: USE is not allowed in a stored procedure.
sql/share/russian/errmsg.txt:
  New error message: USE is not allowed in a stored procedure.
sql/share/serbian/errmsg.txt:
  New error message: USE is not allowed in a stored procedure.
sql/share/slovak/errmsg.txt:
  New error message: USE is not allowed in a stored procedure.
sql/share/spanish/errmsg.txt:
  New error message: USE is not allowed in a stored procedure.
sql/share/swedish/errmsg.txt:
  New error message: USE is not allowed in a stored procedure.
sql/share/ukrainian/errmsg.txt:
  New error message: USE is not allowed in a stored procedure.
sql/sp.cc:
  SPs are now "belong" to a DB and may have qualified names.
  New functions for changing DB ("use") when parsing and invoking SPs.
sql/sp.h:
  New functions for changing DB ("use") when parsing and invoking SPs.
sql/sp_cache.cc:
  Use the qualified name in the SP cache.
sql/sp_head.cc:
  New function for allocating a qualified SP name (used in sql_yacc.yy).
  Change DB when executing an SP (if needed).
  Moved thd_mem_root swap functions from sp_head.h.
sql/sp_head.h:
  New function for allocating a qualified SP name (used in sql_yacc.yy).
  Moved thd_mem_root swap functions to sp_head.cc.
sql/sql_db.cc:
  mysql_change_db() now has optional arguments for use by SP with qualified names
  (for use when reading an SP from database and executing it); also allow "unusing"
  a database, i.e. setting thd->thd to "".
sql/sql_yacc.yy:
  Initialize qualfied SP names correctly.
  USE is no longer allowed in an SP.