CDRIVER-3802 remove bits/signum.h (#685)
CDRIVER-3802 remove bits/signum.h (#685)

Co-authored-by: Dan Bauman <2591e5f46f28d303f9dc027d475a5c60d8dea17a@bauman.space>
beingmeta/mongo-c-driver,beingmeta/mongo-c-driver,mongodb/mongo-c-driver,rcsanchez97/mongo-c-driver,mongodb/mongo-c-driver,rcsanchez97/mongo-c-driver,beingmeta/mongo-c-driver,rcsanchez97/mongo-c-driver,jmikola/mongo-c-driver,beingmeta/mongo-c-driver,jmikola/mongo-c-driver,jmikola/mongo-c-driver,beingmeta/mongo-c-driver,rcsanchez97/mongo-c-driver,beingmeta/mongo-c-driver,rcsanchez97/mongo-c-driver,mongodb/mongo-c-driver,mongodb/mongo-c-driver,mongodb/mongo-c-driver,jmikola/mongo-c-driver,jmikola/mongo-c-driver,rcsanchez97/mongo-c-driver,jmikola/mongo-c-driver,rcsanchez97/mongo-c-driver,jmikola/mongo-c-driver,mongodb/mongo-c-driver,beingmeta/mongo-c-driver,mongodb/mongo-c-driver,beingmeta/mongo-c-driver