fbcode_builder: getdeps: fboss: add libmnl manifest
fbcode_builder: getdeps: fboss: add libmnl manifest

Summary:
This is towards getting open source FBOSS to build using fbcode_builder.
libmnl is one of the dependencies for FBOSS. This patch adds a manifest file
to build the specific version of libmnl for FBOSS.

Reviewed By: wez

Differential Revision: D15633176

fbshipit-source-id: dd51997ae950f53842711fbf2d044e84cdf437e7

facebook/watchman,facebook/watchman,facebook/watchman,wez/watchman,nodakai/watchman,facebook/watchman,facebook/watchman,wez/watchman,wez/watchman,nodakai/watchman,wez/watchman,wez/watchman,wez/watchman,nodakai/watchman,wez/watchman,nodakai/watchman,facebook/watchman,wez/watchman,nodakai/watchman,wez/watchman,nodakai/watchman,nodakai/watchman,facebook/watchman,facebook/watchman,nodakai/watchman,facebook/watchman,nodakai/watchman