build: improve gcc check.
build: improve gcc check.

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