Bug#21103: DATE column not compared as DATE

When comparing a DATE field with a DATETIME constant, we now compare
as DATETIMEs, not as DATEs.  Fix BDB queries to still work.

mysql-test/r/ps_6bdb.result

@@ -3029,25 +3029,25 @@ test_sequence
 -- select .. where date/time column = .. --
 set @arg00= '1991-01-01 01:01:01' ;
 select 'true' as found from t9 
-where c1= 20 and c13= '1991-01-01 01:01:01' and c14= '1991-01-01 01:01:01' and
+where c1= 20 and c13= CAST('1991-01-01 01:01:01' AS DATE) and c14= '1991-01-01 01:01:01' and
 c15= '1991-01-01 01:01:01' and c16= '1991-01-01 01:01:01' and
 c17= '1991-01-01 01:01:01' ;
 found
 true
 select 'true' as found from t9 
-where c1= 20 and c13= @arg00 and c14= @arg00 and c15= @arg00 and c16= @arg00
+where c1= 20 and c13= CAST(@arg00 AS DATE) and c14= @arg00 and c15= @arg00 and c16= @arg00
 and c17= @arg00 ;
 found
 true
 prepare stmt1 from "select 'true' as found from t9 
-where c1= 20 and c13= '1991-01-01 01:01:01' and c14= '1991-01-01 01:01:01' and
+where c1= 20 and c13= CAST('1991-01-01 01:01:01' AS DATE) and c14= '1991-01-01 01:01:01' and
   c15= '1991-01-01 01:01:01' and c16= '1991-01-01 01:01:01' and
   c17= '1991-01-01 01:01:01'" ;
 execute stmt1 ;
 found
 true
 prepare stmt1 from "select 'true' as found from t9 
-where c1= 20 and c13= ? and c14= ? and c15= ? and c16= ? and c17= ?" ;
+where c1= 20 and c13= CAST(? AS DATE) and c14= ? and c15= ? and c16= ? and c17= ?" ;
 execute stmt1 using @arg00, @arg00, @arg00, @arg00, @arg00 ;
 found
 true
@@ -3061,7 +3061,7 @@ c17= CAST('1991-01-01 01:01:01' as datetime) ;
 found
 true
 select 'true' as found from t9 
-where c1= 20 and c13= @arg00 and c14= @arg00 and c15= @arg00 and c16= @arg00
+where c1= 20 and c13= CAST(@arg00 AS DATE) and c14= @arg00 and c15= @arg00 and c16= @arg00
 and c17= @arg00 ;
 found
 true
@@ -3075,7 +3075,7 @@ execute stmt1 ;
 found
 true
 prepare stmt1 from "select 'true' as found from t9 
-where c1= 20 and c13= ? and c14= ? and c15= ? and c16= ? and c17= ?" ;
+where c1= 20 and c13= CAST(? AS DATE) and c14= ? and c15= ? and c16= ? and c17= ?" ;
 execute stmt1 using @arg00, @arg00, @arg00, @arg00, @arg00 ;
 found
 true