Support building the split systemd repository

I plan to roll this out tomorrow (Friday), and then merge systemd into pmaports master (pmaports!5563 (merged)) :>

Depends on: pmbootstrap!2410 (merged)

• Related: #140 (closed)
• Close #144 (closed)
• Close #145 (closed) (staging repo + split repo should work as well)

.ci/pytest-pmb-v2.sh

@@ -89,7 +89,7 @@ pytest \
 	-x \
 	$cov_arg \
 	test \
-		-m "not skip_ci" \
+		-m "not skip_ci and not skip_pmbv2" \
 		"$@"
 
 if command -v coverage >/dev/null; then