sasl: check for {done: 1} when authenticating against GSSAPI.
sasl: check for {done: 1} when authenticating against GSSAPI.

This gets SASL working for me on my test setup. We still need to abstract
this into it's own module and remove the goto's for control flow.

We probably need a maximum number of steps during sasl_client_step()
too.

Additionally, we need some work to verify thread safety.

Convey-Compliance/mongo-c-driver,ajdavis/mongo-c-driver,acmorrow/mongo-c-driver,hanumantmk/libmongoc,remicollet/mongo-c-driver,derickr/mongo-c-driver,u2yg/mongo-c-driver,Convey-Compliance/mongo-c-driver,mongodb/mongo-c-driver,rcsanchez97/mongo-c-driver,beingmeta/mongo-c-driver,bjori/mongo-c-driver,ac000/mongo-c-driver,ajdavis/mongo-c-driver,jmikola/mongo-c-driver,Convey-Compliance/mongo-c-driver,acmorrow/mongo-c-driver,bjori/mongo-c-driver,jqk6/mongo-c-driver,ksuarz/mongo-c-driver,beingmeta/mongo-c-driver,bjori/mongo-c-driver,beingmeta/mongo-c-driver,ajdavis/mongo-c-driver,malexzx/mongo-c-driver,derickr/mongo-c-driver,derickr/mongo-c-driver,derickr/mongo-c-driver,bjori/mongo-c-driver,derickr/mongo-c-driver,rcsanchez97/mongo-c-driver,rcsanchez97/mongo-c-driver,jsbattig/mongo-c-driver,mongodb/mongo-c-driver,acmorrow/mongo-c-driver,rcsanchez97/mongo-c-driver,bjori/mongo-c-driver,remicollet/mongo-c-driver,beingmeta/mongo-c-driver,4Second2None/mongo_C_tmp,bauman/mongo-c-driver,jqk6/mongo-c-driver,bjori/mongo-c-driver,mongodb/mongo-c-driver,ajdavis/mongo-c-driver,Machyne/mongo-c-driver,rcsanchez97/mongo-c-driver,mongodb/mongo-c-driver,ksuarz/mongo-c-driver,chergert/mongo-c-driver-1,Machyne/mongo-c-driver,4Second2None/mongo_C_tmp,christopherjwang/mongo-c-driver,paulmelnikow/mongo-c-driver-1,remicollet/mongo-c-driver,Convey-Compliance/mongo-c-driver,rcsanchez97/mongo-c-driver,malexzx/mongo-c-driver,shelsonjava/mongo-c-driver,jmikola/mongo-c-driver,eugene-convey/mongo-c-driver,ajdavis/mongo-c-driver,bauman/mongo-c-driver,ksuarz/mongo-c-driver,christopherjwang/mongo-c-driver,malexzx/mongo-c-driver,jmikola/mongo-c-driver,ajdavis/mongo-c-driver,ac000/mongo-c-driver,acmorrow/mongo-c-driver,paulmelnikow/mongo-c-driver-1,acmorrow/mongo-c-driver,jmikola/mongo-c-driver,u2yg/mongo-c-driver,mongodb/mongo-c-driver,jsbattig/mongo-c-driver,jsbattig/mongo-c-driver,mschoenlaub/mongo-c-driver,acmorrow/mongo-c-driver,hanumantmk/libmongoc,remicollet/mongo-c-driver,chergert/mongo-c-driver-1,mschoenlaub/mongo-c-driver,jmikola/mongo-c-driver,beingmeta/mongo-c-driver,bjori/mongo-c-driver,jmikola/mongo-c-driver,eugene-convey/mongo-c-driver,beingmeta/mongo-c-driver,bauman/mongo-c-driver,mschoenlaub/mongo-c-driver,mongodb/mongo-c-driver,Machyne/mongo-c-driver,beingmeta/mongo-c-driver,eugene-convey/mongo-c-driver,christopherjwang/mongo-c-driver,u2yg/mongo-c-driver,malexzx/mongo-c-driver,Machyne/mongo-c-driver,mschoenlaub/mongo-c-driver,christopherjwang/mongo-c-driver,u2yg/mongo-c-driver,rcsanchez97/mongo-c-driver,shelsonjava/mongo-c-driver,ac000/mongo-c-driver,jmikola/mongo-c-driver,remicollet/mongo-c-driver,remicollet/mongo-c-driver,chergert/mongo-c-driver-1,derickr/mongo-c-driver,shelsonjava/mongo-c-driver,Convey-Compliance/mongo-c-driver,ksuarz/mongo-c-driver,derickr/mongo-c-driver,ajdavis/mongo-c-driver,mongodb/mongo-c-driver,acmorrow/mongo-c-driver,hanumantmk/libmongoc,paulmelnikow/mongo-c-driver-1,beingmeta/mongo-c-driver,4Second2None/mongo_C_tmp,hanumantmk/libmongoc,jqk6/mongo-c-driver,remicollet/mongo-c-driver