iter: add overflow check in utf-8 string.
iter: add overflow check in utf-8 string.

derickr/libbson,hanumantmk/libbson,mongodbinc-interns/libbson,alexeyvo/libbson,4Second2None/libbson_tmp,rcsanchez97/libbson,derickr/libbson,rayyang2000/libbson,ajdavis/libbson,mongodb/libbson,bjori/libbson,mapr/libbson,jqk6/libbson,mongodbinc-interns/libbson,ksuarz/libbson,Machyne/libbson,rcsanchez97/libbson,alexeyvo/libbson,remicollet/libbson,Machyne/libbson,rayyang2000/libbson,4Second2None/libbson_tmp,4Second2None/libbson_tmp,ajdavis/libbson,bjori/libbson,jqk6/libbson,ajdavis/libbson,hanumantmk/libbson,Convey-Compliance/libbson,jqk6/libbson,jqk6/libbson,rayyang2000/libbson,mapr/libbson,mongodb/libbson,Convey-Compliance/libbson,rcsanchez97/libbson,mongodbinc-interns/libbson,rayyang2000/libbson,ksuarz/libbson,4Second2None/libbson_tmp,paulmelnikow/libbson,derickr/libbson,paulmelnikow/libbson,mongodb/libbson,Machyne/libbson,bjori/libbson,remicollet/libbson,paulmelnikow/libbson,Machyne/libbson,paulmelnikow/libbson,ksuarz/libbson,alexeyvo/libbson,remicollet/libbson,paulmelnikow/libbson,mapr/libbson,derickr/libbson,mongodbinc-interns/libbson,remicollet/libbson,hanumantmk/libbson,hanumantmk/libbson,Convey-Compliance/libbson