ENH added some xorg-x11 CDTs and pixman

[beckermr]

Please see the repo readme for directions on how to make PRs on this repo.

Checklist:

• if you have added a CDT, it appears in the cdt_slugs.yaml file
• if you have changed the CDT generator code (rpm.py), you have bumped
  the build number in conda_build_config.yaml and have remade all of the
  recipes via running python gen_cdt_recipes.py
• if you have added a custom CDT recipe, you have added the name of the CDT
  with custom: true in the cdt_slugs.yaml file.
• all CDT recipes have build number set by {{ cdt_build_number }} for
  old-style/legacy CDTs or {{ cdt_build_number|int + 1000 }} for new-style CDTs
• if you see a warning about a CDT not having a license, you have added the
  license_file key in the cdt_slugs.yaml file with the path to the appropriate
  license in licenses/