positive numbers when no resultset is available": when sending
result set metadata we need to use virtual select_result::send_fields, 
and not address protocol directly, because select_result descendents may 
intercept result set (it's the case for example for SELECT INTO OUTFILE).


sql/sql_class.h:
  A fix for bug#6059 "mysql_stmt_field_count returns positive numbers 
  when no resultset is available": introducing select_result::field_count()
  method to report actual number of fields in a result set, if any result
  set is sent to client.
sql/sql_prepare.cc:
  A fix for bug#6059 "mysql_stmt_field_count returns 
  positive numbers when no resultset is available": when sending
  result set metadata we need to use virtual select_result::send_fields, 
  and not address protocol directly, because select_result descendents may 
  intercept result set (it's the case for example for SELECT INTO OUTFILE).
  Now we need to always have lex->result set if we're in prepared statements.
tests/client_test.c:
  A test case for Bug#6059 "mysql_stmt_field_count returns positive 
  numbers when no resultset is available"