[Chapel Merge] Fix module build for python3

Branch: refs/heads/master
Revision: 9a1e0f7
Author: mppf
Log Message:

Merge pull request #16631 from mppf/fix-build-configs-python3

Fix module build for python3

Follow-up to PR #16560.

  • updates venv-use-sys-python to consider python3 filenames and rewrite
    shebangs in bin/ (see also PR #3571)
  • updates setenv-hpe-cray-ex-x86_64.bash and setenv-xc-x86_64.bash to use
    whichever python find-python.sh gives us but to run
    venv-use-sys-python if it is not the system python
  • updates util/build_configs/setenv-example-3.bash to be more similar to
    the others with a venv target so that it can test the venv build and
    venv-use-sys-python part
  • [x] test_rpm_module.bash succeeds and uses system python for things
    in venv’s bin

Reviewed by @lydia-duncan - thanks!

Modified Files:
M third-party/chpl-venv/venv-use-sys-python.py
M util/build_configs/cray-internal/setenv-hpe-cray-ex-x86_64.bash
M util/build_configs/cray-internal/setenv-xc-x86_64.bash
M util/build_configs/setenv-example-3.bash

Compare: https://github.com/chapel-lang/chapel/compare/9d53743fd5b7...9a1e0f75d0e7