psycopg2 recipe build fail

### Logs

```
[1m[INFO][0m: [36m-> directory context /home/bobf/ex/regression/.buildozer/android/platform/build-arm64-v8a/build/other_builds/psycopg2/arm64-v8a__ndk_target_21/psycopg2[39m
[1m[90m[DEBUG][39m[0m: [90m->[0m running python3 setup.py build_ext --static-libpq[0m
[1m[90m[DEBUG][39m[0m: running build_ext
[1m[90m[DEBUG][39m[0m:
[1m[90m[DEBUG][39m[0m: Error: pg_config executable not found.
[1m[90m[DEBUG][39m[0m:
[1m[90m[DEBUG][39m[0m: pg_config is required to build psycopg2 from source. Please add the directory
[1m[90m[DEBUG][39m[0m: containing pg_config to the $PATH or specify the full executable path with the
[1m[90m[DEBUG][39m[0m: option:
[1m[90m[DEBUG][39m[0m:
[1m[90m[DEBUG][39m[0m: python setup.py build_ext --pg-config /path/to/pg_config build ...
[1m[90m[DEBUG][39m[0m:
[1m[90m[DEBUG][39m[0m: or with the pg_config option in 'setup.cfg'.
[1m[90m[DEBUG][39m[0m:
[1m[90m[DEBUG][39m[0m: If you prefer to avoid building psycopg2 from source, please install the PyPI
[1m[90m[DEBUG][39m[0m: 'psycopg2-binary' package instead.
[1m[90m[DEBUG][39m[0m:
[1m[90m[DEBUG][39m[0m: For further information please check the 'doc/src/install.rst' file (also at
[1m[90m[DEBUG][39m[0m: ).
```

The report identifies the psycopg2 recipe, the setup.py build_ext --static-libpq command, and the pg_config error; start by locating that recipe and checking how its build environment is prepared. Reproduce the Android arm64-v8a build, with success defined as completing the psycopg2 recipe build without the missing pg_config failure.

Written by the indexing model from the issue text.