Channels with regular and extended interface need to live in the same
handle name space otherwise they can't be uniquely identified in the
global channel manager.
CMake 2.8 does not support default visibility on windows.
To allow building tests add the FREERDP_LOCAL define for each
function that is internal to FreeRDP.
When build with testing these functions are exported and available
for use by tests.
Global static variables do not work, if more than one instance
of an RDP client is running in the same process space.
Removed the varaibles where possible and replaced them with
thread local storage where necessary.
