librsocket-cpp: Add new package librsocket-cpp

librsocket-cpp: Add new package librsocket-cpp

C++ implementation of RSocket
RSocket is a binary protocol for use on byte stream transports such as
TCP, WebSockets, and Aeron. (https://rsocket.io/)

This ships with two separte libraries, yarpl and rsocket

Patch 100 is already upstream
(https://github.com/rsocket/rsocket-cpp/commit/862202c6e99a49a8cbd304644d98d3f419b429d8).
Patch 101 in process of upstreaming as it needs to made compatible with
using both gold and ld.

[Dependency of https://github.com/facebook/openr]

Compile tested: openwrt master - nbg6817, arc700

Signed-off-by: Amol Bhave <ambhave@fb.com>