Up to this commit the client and server state machine handling used
different return values for state machine changes.
This is fixed with this commit:
* Use common enum return values
* Use common helper functions
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.
