Enable Starlark `py_runtime`.
I manually built a Bazel and ran tests in rules_python with it; looks to be OK.
Work towards
@@ -61,7 +61,7 @@ exported_rules = {
"+cc_test": cc_test,
"+cc_library": cc_library,
"proto_lang_toolchain": proto_lang_toolchain,
- "-py_runtime": py_runtime,
+ "+py_runtime": py_runtime,
}
# A list of Starlark functions callable from native rules implementation.
