rpmspec: Use explicit value for PYTHONARCHDIR

With the recent update[1] to waf 2.1.5 in upstream Samba, PYTHONARCHDIR
is incorrectly set for Python >= 3.10 causing failures during the build
process. Issue[2] is under scrutiny and in the meantime override the
value by explicit mention with '--pythonarchdir' during configure.

[1] https://gitlab.com/samba-team/samba/-/merge_requests/4040
[2] https://gitlab.com/ita1024/waf/-/issues/2472

Author: anoopcs9

packaging/samba-master.spec.j2

@@ -1175,6 +1175,7 @@ export python_LDFLAGS="$(echo ${LDFLAGS} | sed -e 's/-Wl,-z,defs//g')"
         --with-lockdir=/var/lib/samba/lock \
         --with-statedir=/var/lib/samba \
         --with-cachedir=/var/lib/samba \
+        --pythonarchdir=%{python3_sitearch} \
         --disable-rpath-install \
         --with-shared-modules=%{_samba_modules} \
         --bundled-libraries=%{_samba_libraries} \