erp5: Switch runwsgi to be implemented via pyprog + gpython-interpreter instead of zc.recipe.egg

An example patch of how to convert a program to be run via gpython. For now
there should be no change in semantic, but once we adjust ERP5 interpreter to
activate bstr+ustr as builtin string types by default, it will affect the
programs ran via pyprog infrastructure.

/cc @kazuhiko, @jerome

stack/erp5/buildout.cfg

@@ -85,6 +85,7 @@ parts +=
 
 # some additional utils
   zodbpack
+  runwsgi
 
 # Create instance template
   template
@@ -476,6 +477,15 @@ pre-initialization +=
 eggs += ${eggs:eggs}
 extra-paths += ${eggs:extra-paths}
 
+# erp5-pyprog is similar to pyprog macro and should be used by python-based
+# programs instantiated in ERP5 software-release.
+[erp5-pyprog]
+<= pyprog
+exe = ${buildout:bin-directory}/${:_buildout_section_name_}
+python-interpreter = erp5-python-interpreter
+# by default no need for extra eggs in addition to eggs provided by interpreter
+eggs =
+
 [erp5-python-interpreter-jupyter]
 <= erp5-python-interpreter
 interpreter = pythonwitheggs_jupyter
@@ -634,10 +644,8 @@ eggs =
   Zope
 
 entry-points =
-  runwsgi=Products.ERP5.bin.zopewsgi:runwsgi
 scripts =
   apachedex
-  runwsgi
   runzeo
   tidstoraged
   tidstorage_repozo
@@ -753,6 +761,11 @@ scripts =
 depends =
   ${slapos-toolbox-dependencies:eggs}
 
+[runwsgi]
+<= erp5-pyprog
+entry = Products.ERP5.bin.zopewsgi:runwsgi
+
+
 [versions]
 # See ../../software/neoppod/software-common.cfg for versions common with NEO:
 #  neoppod, mysqlclient, slapos.recipe.template