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- [x] Add new / update outdated documentation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: libxml
  version: 2.9.10

source:
  sha256: aafee193ffb8fe0c82d4afef6ef91972cbaf5feea100edc2f262750611b4be1f
  url: http://xmlsoft.org/sources/libxml2-2.9.10.tar.gz

requirements:
  host:
    - zlib
    - libiconv

build:
  type: static_library
  script: |
    emconfigure ./configure \
        CFLAGS="-fPIC" \
        --disable-dependency-tracking \
        --disable-shared \
        --without-python \
        --with-iconv="${WASM_LIBRARY_DIR}/lib" \
        --with-zlib="${WASM_LIBRARY_DIR}/lib" \
        --with-lzma="no" \
        --prefix=${WASM_LIBRARY_DIR}
    emmake make -j ${PYODIDE_JOBS:-3}
    emmake make install

package:
  name: libxml
  version: 2.9.10

source:
  sha256: aafee193ffb8fe0c82d4afef6ef91972cbaf5feea100edc2f262750611b4be1f
  url: http://xmlsoft.org/sources/libxml2-2.9.10.tar.gz

requirements:
  host:
    - zlib
    - libiconv

build:
  type: static_library
  script: |
    emconfigure ./configure \
        CFLAGS="-fPIC" \
        --disable-dependency-tracking \
        --disable-shared \
        --without-python \
        --with-iconv="${WASM_LIBRARY_DIR}/lib" \
        --with-zlib="${WASM_LIBRARY_DIR}/lib" \
        --with-lzma="no" \
        --prefix=${WASM_LIBRARY_DIR}
    emmake make -j ${PYODIDE_JOBS:-3}
    emmake make install
