Fixes in opt_range.cc: ROR plan choice code

 * Removed unused parameters 
 * Fixed several cost calculation errors in ror_intersect_add
 * Better code structure for ror_intersect_add and get_best_ror_intersect


include/my_bitmap.h:
  Comments added
mysql-test/r/index_merge_innodb.result:
  Test results updated
mysql-test/r/index_merge_ror_cpk.result:
  Test results updated.
mysql-test/t/index_merge_innodb.test:
  Drop all tables after use
sql/opt_range.cc:
  Fixes in ROR plan choice code
  * Removed unused parameters 
  * Fixed several cost calculation errors in ror_intersect_add
  * Better code structure for ror_intersect_add and get_best_ror_intersect

include/my_bitmap.h

@@ -24,7 +24,7 @@
 typedef struct st_bitmap
 {
   uchar *bitmap;
-  uint bitmap_size;
+  uint bitmap_size; /* number of bytes occupied by the above */
   /*
      mutex will be acquired for the duration of each bitmap operation if
      thread_safe flag in bitmap_init was set.  Otherwise, we optimize by not

mysql-test/r/index_merge_innodb.result

-drop table if exists t1;
+drop table if exists t1,t2;
 create table t1
 (
 key1 int not null, 

mysql-test/r/index_merge_ror_cpk.result

@@ -26,7 +26,7 @@ primary key (pk1, pk2)
 ) engine=innodb;
 explain select * from t1 where pk1 = 1 and pk2 < 80  and key1=0;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ref	PRIMARY,key1	PRIMARY	4	const	1	Using where
+1	SIMPLE	t1	range	PRIMARY,key1	PRIMARY	8	NULL	9	Using where
 select * from t1 where pk1 = 1 and pk2 < 80  and key1=0;
 pk1	pk2	key1	key2	pktail1ok	pktail2ok	pktail3bad	pktail4bad	pktail5bad	pk2copy	badkey	filler1	filler2
 1	10	0	0	0	0	0	0	0	10	0	filler-data-10	filler2

mysql-test/t/index_merge_innodb.test

@@ -4,7 +4,7 @@
 -- source include/have_innodb.inc
 
 --disable_warnings
-drop table if exists t1;
+drop table if exists t1,t2;
 --enable_warnings
 
 create table t1