The AsBinary function returns VARCHAR data type with binary collation.
It can cause problem for clients that treat that kind of data as
different from BLOB type.
So now AsBinary returns BLOB.


mysql-test/r/gis.result:
  result fixed
mysql-test/t/gis.test:
  test case added
sql/item_geofunc.h:
  Now we return MYSQL_TYPE_BLOB for asBinary function