Add buildtool_export_depend on ament_cmake_ros_core

[sloretz]

Description

#548 added ament_export_dependencies(... ament_cmake_ros_core). This is probably correct, because the rcutils targets now reference an ament_cmake_ros_core target. However, we need to tell downstream packages to install that dependency.

Fixes build errors like this one:

https://build.ros2.org/job/Rbin_uN64__rmw_security_common__ubuntu_noble_amd64__binary/59/console

05:27:03 CMake Error at /opt/ros/rolling/share/rcutils/cmake/ament_cmake_export_dependencies-extras.cmake:21 (find_package):
05:27:03   By not providing "Findament_cmake_ros_core.cmake" in CMAKE_MODULE_PATH this
05:27:03   project has asked CMake to find a package configuration file provided by
05:27:03   "ament_cmake_ros_core", but CMake did not find one.
05:27:03 
05:27:03   Could not find a package configuration file provided by
05:27:03   "ament_cmake_ros_core" with any of the following names:
05:27:03 
05:27:03     ament_cmake_ros_coreConfig.cmake
05:27:03     ament_cmake_ros_core-config.cmake
05:27:03 
05:27:03   Add the installation prefix of "ament_cmake_ros_core" to CMAKE_PREFIX_PATH
05:27:03   or set "ament_cmake_ros_core_DIR" to a directory containing one of the
05:27:03   above files.  If "ament_cmake_ros_core" provides a separate development
05:27:03   package or SDK, be sure it has been installed.
05:27:03 Call Stack (most recent call first):
05:27:03   /opt/ros/rolling/share/rcutils/cmake/rcutilsConfig.cmake:41 (include)
05:27:03   CMakeLists.txt:22 (find_package)

Is this user-facing behavior change?

Did you use Generative AI?

no

Additional Information

[sloretz]

CI (testing just rcutils)

• Linux
• Linux-aarch64
• Linux-rhel
• Windows