Don't encode the architecture etc. in the Python 3 name.

GARStow will rebuild the package anyway when the Python version changes, so
this avoids needing arch-specific export.mk files.

--- talloc-2.3.2/buildtools/wafsamba/samba_python.py	2021-01-25 08:35:07.413710600 +0000
+++ talloc-2.3.2/buildtools/wafsamba/samba_python.py	2021-01-25 19:20:01.323769985 +0000
@@ -58,8 +58,7 @@
 def _check_python_headers(conf):
     conf.check_python_headers()
 
-    abi_pattern = os.path.splitext(conf.env['pyext_PATTERN'])[0]
-    conf.env['PYTHON_SO_ABI_FLAG'] = abi_pattern % ''
+    conf.env['PYTHON_SO_ABI_FLAG'] = ''
     conf.env['PYTHON_LIBNAME_SO_ABI_FLAG'] = (
         conf.env['PYTHON_SO_ABI_FLAG'].replace('_', '-'))