bpo-35348: Fix platform.architecture() (GH-11159)

Make platform.architecture() parsing of "file" command output more
reliable:

* Add the "-b" option to the "file" command to omit the filename;
* Force the usage of the C locale;
* Search also the "shared object" pattern.

Co-Authored-By: Serhiy Storchaka <storchaka@gmail.com>