FAILS IN SET_FIELD_ITERATOR

(Former 59299)

When a PROCEDURE does a natural join, resolving of which columns are
used in the join is done only once; consecutive CALLs to the procedure
will reuse this information:

CREATE PROCEDURE proc() SELECT * FROM t1 NATURAL JOIN v1;
CALL proc();   <- natural join columns resolved here
CALL proc();   <- reuse resolved NJ columns from first CALL

The second CALL knows that it can reuse the resolved NJ columns because
the first CALL sets st_select_lex::first_natural_join_processing=false.
The problem in this bug was that the table the view v1 depends on 
changed between CREATE PROCEDURE and the first CALL: 

CREATE PROCEDURE...
ALTER TABLE t2 CHANGE COLUMN a b CHAR;
CALL proc();   <- error when resolving natural join columns
CALL proc();   <- tries to reuse from first CALL => crash

The fix for this bug is to set first_natural_join_processing= FALSE iff
the natural join columns resolving was successful.


mysql-test/r/sp.result:
  Add test for bug 11766234
mysql-test/t/sp.test:
  Add test for bug 11766234
sql/sql_base.cc:
  Set first_natural_join_processing= FALSE iff the natural join columns resolving was successful.