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- [x] Add new / update outdated documentation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: iniconfig
  version: 1.1.1
  top-level:
    - iniconfig
source:
  sha256: 011e24c64b7f47f6ebd835bb12a743f2fbe9a26d4cecaa7f53bc4f35ee9da8b3
  url: https://files.pythonhosted.org/packages/9b/dd/b3c12c6d707058fa947864b67f0c4e0c39ef8610988d7baea9578f3c48f3/iniconfig-1.1.1-py2.py3-none-any.whl
about:
  home: http://github.com/RonnyPfannschmidt/iniconfig
  PyPI: https://pypi.org/project/iniconfig
  summary: "iniconfig: brain-dead simple config-ini parsing"
  license: MIT License

package:
  name: iniconfig
  version: 1.1.1
  top-level:
    - iniconfig
source:
  sha256: 011e24c64b7f47f6ebd835bb12a743f2fbe9a26d4cecaa7f53bc4f35ee9da8b3
  url: https://files.pythonhosted.org/packages/9b/dd/b3c12c6d707058fa947864b67f0c4e0c39ef8610988d7baea9578f3c48f3/iniconfig-1.1.1-py2.py3-none-any.whl
about:
  home: http://github.com/RonnyPfannschmidt/iniconfig
  PyPI: https://pypi.org/project/iniconfig
  summary: "iniconfig: brain-dead simple config-ini parsing"
  license: MIT License
