scanpypi: rework runtime dependency handling

In most cases Python's package dependencies found in setup.py are
runtime dependencies and hence don't need to be mentioned in *.mk
file.

Also add '# runtime' tag to select statements in Config.in.

__create_mk_requirements() itself is left for future uses (cffi backend
handling etc.).

Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

support/scripts/scanpypi

@@ -466,8 +466,6 @@ class BuildrootPackage():
         lines += self.__create_mk_download_info()
         lines += self.__create_mk_setup()
         lines += self.__create_mk_license()
-        if self.pkg_req:
-            lines += self.__create_mk_requirements()
 
         lines.append('\n')
         lines.append('$(eval $(python-package))')
@@ -518,7 +516,7 @@ class BuildrootPackage():
         lines.append(bool_line)
         if self.pkg_req:
             for dep in self.pkg_req:
-                dep_line = '\tselect BR2_PACKAGE_{req}\n'.format(
+                dep_line = '\tselect BR2_PACKAGE_{req} # runtime\n'.format(
                     req=dep.upper().replace('-', '_'))
                 lines.append(dep_line)