rostest: add catkin devel space the CMAKE_FIND_ROOT_PATH
rostest: add catkin devel space the CMAKE_FIND_ROOT_PATH

Rostest depends on its own package and therefore needs to search
in the devel space for the rostestConfig.cmake during native
build.

| CMake Error at /.../usr/share/catkin/cmake/find_program_required.cmake:5 (message):
|   rostest not found
|

Signed-off-by: Stefan Herbrechtsmeier <eb0877843acc39f8ef6f7269937dee931c372d23@herbrechtsmeier.net>

bulwahn/meta-ros,rapyuta/meta-ros,simium/meta-ros,bmwcarit/meta-ros,rapyuta/meta-ros,simium/meta-ros,KristofRobot/meta-ros,bmwcarit/meta-ros,KristofRobot/meta-ros,bulwahn/meta-ros,bulwahn/meta-ros,bmwcarit/meta-ros,bmwcarit/meta-ros,rapyuta/meta-ros,simium/meta-ros