* 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