build: bump libbson for atexit fix.

Christian Hergert · Christian Hergert · commit 8dc66c125597 · 2014-07-09T13:32:20.000-07:00
diff --git a/src/libbson b/src/libbson
@@ -1 +1 @@
-Subproject commit faf7d05c6d30747e9dda9740bef442ea44735150
+Subproject commit 39be79f270d134f6c47b8b88f77cc049908fbc95
