Export libraries to trigger hooks.

[nuclearsandwich]

Add ament_export_libraries calls to export libraries and set necessary environment hooks. The rviz packages are some of a handful which install libraries exporting them.

In conversation with @wjwwood we surmised that this was likely a small oversight rather than something that was done intentionally.

Connects to ros2/ros_workspace#10

[wjwwood]

I wonder if this is redundant with ament_export_interfaces, or rather whether or not that function should also extend the library paths.

@dirk-thomas what do you think?

[dirk-thomas]

While both do kind of the same thing they work differently:

• ament_export_interfaces is used to export the targets via CMake install(EXPORT ...)
• ament_export_libraries exports libraries using the variable <pkgname>_LIBRARIES

Both make sense depending on how downstream packages want to use them.

Since the target is a library ament_export_interfaces should pass the option HAS_LIBRARY_TARGET (see https://github.com/ament/ament_cmake/blob/88add8cab0ca579e89e95b3ab343af319c163195/ament_cmake_export_interfaces/cmake/ament_export_interfaces.cmake#L22-L24).

HAS_LIBRARY_TARGET

[nuclearsandwich]

I've updated this PR to use the HAS_LIBRARY_TARGET option rather than ament_export_libraries as all I needed was the environment hook to be set.

I swapped rather than did both since I think it's reasonable to make the minimal change unless maintainers prefer otherwise.

[nuclearsandwich]

• Linux
• Linux-aarch64
• macOS
• Windows

[wjwwood]

@mjcarroll you might want to consider this pr in the migration of the yaml cpp stuff.