Add glib to host deps to build gts stuff + add ffmpeg

[Tobias-Fischer]

Checklist

• Used a personal fork of the feedstock to propose changes
• Bumped the build number (if the version is unchanged)
• Reset the build number to 0 (if the version changed)
• Re-rendered with the latest conda-smithy (Use the phrase @conda-forge-admin, please rerender in a comment in this PR for automated rerendering)
• Ensured the license file is being packaged.

[conda-forge-linter]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe) and found it was in an excellent condition.

[Tobias-Fischer]

@conda-forge-admin, please rerender

[traversaro]

Something else that I noticed is missing is ffmpeg, but probably that is not strictly necessary for gazebo.

[Tobias-Fischer]

Thanks for the hint - I added it and it seems to work 👍

[Tobias-Fischer]

Fix #15

[Tobias-Fischer]

@seanyen - all green, this is ready to be merged

[traversaro]

The regression fixed by this PR was catched also by my nightly CI in https://github.com/robotology/robotology-superbuild/runs/1356099458 :

CMake Error at /usr/share/miniconda/envs/test/share/cmake-3.18/Modules/CMakeFindDependencyMacro.cmake:47 (find_package):
  By not providing "Findignition-common3-graphics.cmake" in CMAKE_MODULE_PATH
  this project has asked CMake to find a package configuration file provided
  by "ignition-common3-graphics", but CMake did not find one.

  Could not find a package configuration file provided by
  "ignition-common3-graphics" (requested version 3.7.0) with any of the
  following names:

    ignition-common3-graphicsConfig.cmake
    ignition-common3-graphics-config.cmake

  Add the installation prefix of "ignition-common3-graphics" to
  CMAKE_PREFIX_PATH or set "ignition-common3-graphics_DIR" to a directory
  containing one of the above files.  If "ignition-common3-graphics" provides
  a separate development package or SDK, be sure it has been installed.
Call Stack (most recent call first):
  /usr/share/miniconda/envs/test/lib/cmake/ignition-common3/ignition-common3-config.cmake:193 (find_dependency)
  /usr/share/miniconda/envs/test/lib/cmake/gazebo/gazebo-config.cmake:209 (find_package)
  cmake/BuildGazeboYARPPlugins.cmake:31 (find_package)
  build/install/share/YCM/modules/FindOrBuildPackage.cmake:215 (include)
  CMakeLists.txt:136 (find_or_build_package)

It would be nice to have some option in ignition-cmake upstream to have a clear error if the dependency of some components are missing instead of silently disabling the component, see gazebosim/gz-cmake#63 .

[Tobias-Fischer]

Here we also have the chance to test whether the library was created - feel free to add these tests @traversaro

[traversaro]

Good point! I will open an issue to not forget about it.