Remove conflict between function and struct names
Remove conflict between function and struct names

There was a conflict between the function `bcon_extract_ctx` and the raw struct name (which is typedef'ed to `bcon_extract_ctx_t` anyway). A similar situation happened for `bcon_append_ctx`. This change simply renames the raw names, since they are never used.
ajdavis/libbson,ajdavis/libbson,ksuarz/libbson,mongodb/libbson,4Second2None/libbson_tmp,mongodb/libbson,4Second2None/libbson_tmp,rcsanchez97/libbson,mapr/libbson,remicollet/libbson,alexeyvo/libbson,mongodbinc-interns/libbson,ajdavis/libbson,Machyne/libbson,jqk6/libbson,alexeyvo/libbson,Convey-Compliance/libbson,derickr/libbson,paulmelnikow/libbson,Machyne/libbson,paulmelnikow/libbson,Convey-Compliance/libbson,ksuarz/libbson,mapr/libbson,jqk6/libbson,Machyne/libbson,paulmelnikow/libbson,remicollet/libbson,rcsanchez97/libbson,derickr/libbson,4Second2None/libbson_tmp,Machyne/libbson,bjori/libbson,rayyang2000/libbson,alexeyvo/libbson,4Second2None/libbson_tmp,mongodbinc-interns/libbson,ksuarz/libbson,rayyang2000/libbson,paulmelnikow/libbson,rcsanchez97/libbson,Convey-Compliance/libbson,jqk6/libbson,mongodb/libbson,remicollet/libbson,mongodbinc-interns/libbson,bjori/libbson,paulmelnikow/libbson,rayyang2000/libbson,bjori/libbson,jqk6/libbson,mongodbinc-interns/libbson,derickr/libbson,remicollet/libbson,rayyang2000/libbson,mapr/libbson,derickr/libbson