Remove thrift from the include path of thrift-generated files
Remove thrift from the include path of thrift-generated files

It is not clear why this is necessary, see: 
* https://github.com/robotology/yarp/issues/1092 
* https://github.com/robotology/yarp/issues/2142

However, the new style (without the prepended "thrift") seems to be working fine on both YARP 3.3 and master, 
so given that iDynTree 1.0 now requires YARP 3.3 as the minimum version, I think it is ok to just fix the issue by 
removing the "thrift" directory.
robotology/idyntree,robotology/idyntree,robotology/idyntree,robotology/idyntree,robotology/idyntree