Duplicate maria_add_gis_sp script in the sources

There are two scripts in 10.1 tree:
maria_add_gis_sp_bootstrap.sql
maria_add_gis_sp.sql
They look exactly the same, minus formatting and a comment. I suppose the one should be enough (if you decide to keep the second one, please make sure mysql_install_db and debian file lists are also updated, they now expect the maria_add_gis_sp_bootstrap.sql).