wifi_files: client interface stats, convert to C++

1. client interface stats
   Rearrange code to move stats to a separate struct.
   For AP, output every associated client.
   For STA, output stats of local client interface.

2. convert to C++, remove libglib dependency
   libglib is one of the largest files in the GFMN100
   filesystem, and appears to only be used by wifi_files
   for g_hash support. Convert wifi_files to C++ and use
   unordered_map instead. libstdc++ is even larger than
   libglib but is used by a bunch of stuff in the system
   already, so we're better off being dependant on it
   than on glib.

Change-Id: Ib454830cf6298729c23cf1caddc0ff880f573a66
4 files changed