Nghttp2 v1.39.2

The new version fixes two CVE vulnerabilitites - CVE-2019-9511 and CVE-2019-9513.

Additionally they list "Add nghttp2_option_set_max_outbound_ack API function" and "nghttpx: Fix request stall".

https://github.com/nghttp2/nghttp2/releases

It is in custombuild now.