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- [x] Add new / update outdated documentation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: sympy
  version: 1.11.1
  top-level:
    - isympy
    - sympy
requirements:
  run:
    - distutils
    - mpmath
source:
  sha256: 938f984ee2b1e8eae8a07b884c8b7a1146010040fccddc6539c54f401c8f6fcf
  url: https://files.pythonhosted.org/packages/2d/49/a2d03101e2d28ad528968144831d506344418ef1cc04839acdbe185889c2/sympy-1.11.1-py3-none-any.whl
about:
  home: https://sympy.org
  PyPI: https://pypi.org/project/sympy
  summary: Computer algebra system (CAS) in Python
  license: BSD

package:
  name: sympy
  version: 1.11.1
  top-level:
    - isympy
    - sympy
requirements:
  run:
    - distutils
    - mpmath
source:
  sha256: 938f984ee2b1e8eae8a07b884c8b7a1146010040fccddc6539c54f401c8f6fcf
  url: https://files.pythonhosted.org/packages/2d/49/a2d03101e2d28ad528968144831d506344418ef1cc04839acdbe185889c2/sympy-1.11.1-py3-none-any.whl
about:
  home: https://sympy.org
  PyPI: https://pypi.org/project/sympy
  summary: Computer algebra system (CAS) in Python
  license: BSD
