Keep CMAKE_FIND_ROOT_PATH clean during incremental builds
Keep CMAKE_FIND_ROOT_PATH clean during incremental builds

This the correct way to fix 920879449fc7f943e5703b050565240ada2d9f3d

Change-Id: I0e2a23abd5f8ab35d164246030c71c0c5e5efd35
Reviewed-on: http://gerrit.aldebaran.lan:8080/13859
Reviewed-by: ckilner <3484075e8fc074f79e3af104726e0e82624120eb@aldebaran-robotics.com>
Tested-by: gerrit
Reviewed-by: dmerejkowsky <1e4b13000fa8777df4cefd2fd8215187e3deb062@aldebaran-robotics.com>

dmerejkowsky/qibuild,dmerejkowsky/qibuild,aldebaran/qibuild,dmerejkowsky/qibuild,dmerejkowsky/qibuild,aldebaran/qibuild,aldebaran/qibuild,aldebaran/qibuild,dmerejkowsky/qibuild