fix mongoc_collection_command test for MongoDB 3.1
fix mongoc_collection_command test for MongoDB 3.1

The test had been querying collections with random names like
$cmd.sys.inprog_12345, which returned the currentOp, the same as
$cmd.sys.inprog, on legacy servers, but not since SERVER 7775.
Now if we query "$cmd.sys.inprog" exactly, the test still works.

beingmeta/mongo-c-driver,bauman/mongo-c-driver,ac000/mongo-c-driver,paulmelnikow/mongo-c-driver-1,malexzx/mongo-c-driver,bjori/mongo-c-driver,acmorrow/mongo-c-driver,beingmeta/mongo-c-driver,derickr/mongo-c-driver,mongodb/mongo-c-driver,acmorrow/mongo-c-driver,eugene-convey/mongo-c-driver,beingmeta/mongo-c-driver,ksuarz/mongo-c-driver,bjori/mongo-c-driver,acmorrow/mongo-c-driver,jmikola/mongo-c-driver,derickr/mongo-c-driver,u2yg/mongo-c-driver,ajdavis/mongo-c-driver,ajdavis/mongo-c-driver,chergert/mongo-c-driver-1,ksuarz/mongo-c-driver,shelsonjava/mongo-c-driver,bauman/mongo-c-driver,mongodb/mongo-c-driver,beingmeta/mongo-c-driver,ksuarz/mongo-c-driver,mschoenlaub/mongo-c-driver,mschoenlaub/mongo-c-driver,u2yg/mongo-c-driver,rcsanchez97/mongo-c-driver,shelsonjava/mongo-c-driver,bjori/mongo-c-driver,eugene-convey/mongo-c-driver,ksuarz/mongo-c-driver,jmikola/mongo-c-driver,mschoenlaub/mongo-c-driver,christopherjwang/mongo-c-driver,rcsanchez97/mongo-c-driver,Machyne/mongo-c-driver,rcsanchez97/mongo-c-driver,acmorrow/mongo-c-driver,jmikola/mongo-c-driver,mongodb/mongo-c-driver,derickr/mongo-c-driver,beingmeta/mongo-c-driver,Machyne/mongo-c-driver,malexzx/mongo-c-driver,beingmeta/mongo-c-driver,jmikola/mongo-c-driver,jsbattig/mongo-c-driver,mongodb/mongo-c-driver,bjori/mongo-c-driver,ajdavis/mongo-c-driver,derickr/mongo-c-driver,mongodb/mongo-c-driver,ac000/mongo-c-driver,u2yg/mongo-c-driver,malexzx/mongo-c-driver,paulmelnikow/mongo-c-driver-1,chergert/mongo-c-driver-1,Convey-Compliance/mongo-c-driver,bjori/mongo-c-driver,mongodb/mongo-c-driver,acmorrow/mongo-c-driver,ajdavis/mongo-c-driver,jsbattig/mongo-c-driver,mschoenlaub/mongo-c-driver,jmikola/mongo-c-driver,derickr/mongo-c-driver,u2yg/mongo-c-driver,Machyne/mongo-c-driver,rcsanchez97/mongo-c-driver,jmikola/mongo-c-driver,mongodb/mongo-c-driver,malexzx/mongo-c-driver,bauman/mongo-c-driver,derickr/mongo-c-driver,shelsonjava/mongo-c-driver,beingmeta/mongo-c-driver,Convey-Compliance/mongo-c-driver,bjori/mongo-c-driver,christopherjwang/mongo-c-driver,remicollet/mongo-c-driver,jmikola/mongo-c-driver,ajdavis/mongo-c-driver,remicollet/mongo-c-driver,jsbattig/mongo-c-driver,jqk6/mongo-c-driver,Convey-Compliance/mongo-c-driver,Convey-Compliance/mongo-c-driver,acmorrow/mongo-c-driver,paulmelnikow/mongo-c-driver-1,Machyne/mongo-c-driver,beingmeta/mongo-c-driver,eugene-convey/mongo-c-driver,remicollet/mongo-c-driver,christopherjwang/mongo-c-driver,remicollet/mongo-c-driver,ac000/mongo-c-driver,rcsanchez97/mongo-c-driver,rcsanchez97/mongo-c-driver,remicollet/mongo-c-driver,remicollet/mongo-c-driver,Convey-Compliance/mongo-c-driver,ajdavis/mongo-c-driver,rcsanchez97/mongo-c-driver,acmorrow/mongo-c-driver,jqk6/mongo-c-driver,jqk6/mongo-c-driver,bjori/mongo-c-driver,derickr/mongo-c-driver,christopherjwang/mongo-c-driver,chergert/mongo-c-driver-1,ajdavis/mongo-c-driver,remicollet/mongo-c-driver