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- [x] Add new / update outdated documentation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: pyheif
  version: 0.7.1
source:
  url: https://files.pythonhosted.org/packages/f3/2f/0492ad16c6936944bf9575a789e2dd6af4a27eb2475a04fb02cf84b2a5db/pyheif-0.7.1.tar.gz
  sha256: 86a5c5174379d7146b5ed1a68892faf7268a135fb7f5039a011bfb7a6e903200
requirements:
  run:
    - cffi
  host:
    - cffi
    - libheif
build:
  vendor-sharedlib: true
  script: |
    sed -i "s@include_dirs = \[@include_dirs = ['\\${WASM_LIBRARY_DIR}/include', @" libheif/libheif_build.py
    sed -i "s@library_dirs = \[@library_dirs = ['\\${WASM_LIBRARY_DIR}/lib', @" libheif/libheif_build.py
test:
  imports:
    - pyheif
about:
  home: https://github.com/carsales/pyheif
  PyPI: https://pypi.org/project/pyheif
  summary: Python 3.6+ interface to libheif library

package:
  name: pyheif
  version: 0.7.1
source:
  url: https://files.pythonhosted.org/packages/f3/2f/0492ad16c6936944bf9575a789e2dd6af4a27eb2475a04fb02cf84b2a5db/pyheif-0.7.1.tar.gz
  sha256: 86a5c5174379d7146b5ed1a68892faf7268a135fb7f5039a011bfb7a6e903200
requirements:
  run:
    - cffi
  host:
    - cffi
    - libheif
build:
  vendor-sharedlib: true
  script: |
    sed -i "s@include_dirs = \[@include_dirs = ['\\${WASM_LIBRARY_DIR}/include', @" libheif/libheif_build.py
    sed -i "s@library_dirs = \[@library_dirs = ['\\${WASM_LIBRARY_DIR}/lib', @" libheif/libheif_build.py
test:
  imports:
    - pyheif
about:
  home: https://github.com/carsales/pyheif
  PyPI: https://pypi.org/project/pyheif
  summary: Python 3.6+ interface to libheif library
