Closes https://github.com/pyodide/pyodide/issues/604

This creates an installable `pyodide-build` Python package that we can also upload to PyPi under https://pypi.org/project/pyodide-build/ (currently uploaded the dev version to reserve the name).

There is also the identically named `pyodide-build` CLI command which replaces `bin/pyodide`.

The short term goals is to use fewer hacks with `PATH` and `PYTHONPATH`. Long term goal make it a user facing interface for building packages instead of the Makefile.
Create an installable pyodide-build package. Closes https://github.com/pyodide/pyodide/issues/604

This creates an installable `pyodide-build` Python package that we can also upload to PyPi under https://pypi.org/project/pyodide-build/ (currently uploaded the dev version to reserve the name).

There is also the identically named `pyodide-build` CLI command which replaces `bin/pyodide`.

The short term goals is to use fewer hacks with `PATH` and `PYTHONPATH`. Long term goal make it a user facing interface for building packages instead of the Makefile.
package:
  name: retrying
  version: 1.3.3
source:
  sha256: 08c039560a6da2fe4f2c426d0766e284d3b736e355f8dd24b37367b0bb41973b
  url: https://files.pythonhosted.org/packages/44/ef/beae4b4ef80902f22e3af073397f079c96969c69b2c7d52a57ea9ae61c9d/retrying-1.3.3.tar.gz
requirements:
  run:
    - six
test:
  imports:
  - retrying

package:
  name: retrying
  version: 1.3.3
source:
  sha256: 08c039560a6da2fe4f2c426d0766e284d3b736e355f8dd24b37367b0bb41973b
  url: https://files.pythonhosted.org/packages/44/ef/beae4b4ef80902f22e3af073397f079c96969c69b2c7d52a57ea9ae61c9d/retrying-1.3.3.tar.gz
requirements:
  run:
    - six
test:
  imports:
  - retrying
