rds_index*free procedures shall be able to handle NULL
rds_index*free procedures shall be able to handle NULL

The very most of the OpenSCAP _free routines can take NULL pointer so
the caller does not need to care. rds_index*free procedures should not
be an exception.

mpreisler/openscap,OpenSCAP/openscap,OpenSCAP/openscap,ybznek/openscap,jan-cerny/openscap,openprivacy/openscap,Hexadorsimal/openscap,jan-cerny/openscap,jan-cerny/openscap,Hexadorsimal/openscap,postfix/openscap,jan-cerny/openscap,redhatrises/openscap,jan-cerny/openscap,OpenSCAP/openscap,mpreisler/openscap,redhatrises/openscap,redhatrises/openscap,mpreisler/openscap,redhatrises/openscap,openprivacy/openscap,mpreisler/openscap,Hexadorsimal/openscap,postfix/openscap,redhatrises/openscap,ybznek/openscap,openprivacy/openscap,postfix/openscap,Hexadorsimal/openscap,postfix/openscap,ybznek/openscap,OpenSCAP/openscap,mpreisler/openscap,postfix/openscap,ybznek/openscap,redhatrises/openscap,openprivacy/openscap,postfix/openscap,mpreisler/openscap,OpenSCAP/openscap,ybznek/openscap,ybznek/openscap,Hexadorsimal/openscap,Hexadorsimal/openscap,OpenSCAP/openscap,jan-cerny/openscap,openprivacy/openscap,openprivacy/openscap