BLD Add DISTDIR variable. ### Description

Adds `DISTDIR` env variable that points to the directory where libraries should be copied to when building shared libraries with recipe.

### Checklists

- [x] Add new / update outdated documentation

package:
  name: packaging
  version: "21.3"
  top-level:
    - packaging
source:
  sha256: dd47c42927d89ab911e606518907cc2d3a1f38bbd026385970643f9c5b8ecfeb
  url: https://files.pythonhosted.org/packages/df/9e/d1a7217f69310c1db8fdf8ab396229f55a699ce34a203691794c5d1cad0c/packaging-21.3.tar.gz

  patches:
    - patches/allow-cpp310-none-any-tag.patch

requirements:
  run:
    - pyparsing
about:
  home: https://github.com/pypa/packaging
  PyPI: https://pypi.org/project/packaging
  summary: Core utilities for Python packages
  license: BSD-2-Clause or Apache-2.0

package:
  name: packaging
  version: "21.3"
  top-level:
    - packaging
source:
  sha256: dd47c42927d89ab911e606518907cc2d3a1f38bbd026385970643f9c5b8ecfeb
  url: https://files.pythonhosted.org/packages/df/9e/d1a7217f69310c1db8fdf8ab396229f55a699ce34a203691794c5d1cad0c/packaging-21.3.tar.gz

  patches:
    - patches/allow-cpp310-none-any-tag.patch

requirements:
  run:
    - pyparsing
about:
  home: https://github.com/pypa/packaging
  PyPI: https://pypi.org/project/packaging
  summary: Core utilities for Python packages
  license: BSD-2-Clause or Apache-2.0
