xvid: serialize make

Closes #17300.
Allow specifying a name attribute for X11Dependency
DependencyCollector: return created dep from #add
Generate options for optional and recommended requirements
Filter optional and reccommended requirements
LanguageModuleDependency: call super() to generate tags list

Fixes #17379.
Elixir 0.8.0

Update to latest Elixir and make head depend on the
master branch, since now it is stable enough.

Closes #17380.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>