NS_Emulation: Add [optional] support for FrameRelay transport

This adds a NS_Provider_FR which interfaces between FrameRelay_Emulation
and NS_Emulation.  Include support for it only if enabled at compile
time to avoid pulling in a dependency on the FrameRelay stack for every
user of NS_Emulation.

Change-Id: I42ca811d23e383e362d2527c8ff2c916a62a5b42
4 files changed