CI: Import sysrepo

...and also ensure that we build sysrepo & libyang first, so that an
eventual failure breaks the build early.

Change-Id: I2a482624da1dee99fbdf98054a7c66e440cf3998
diff --git a/.gitmodules b/.gitmodules
index 5e10dfb..3a4470e 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -16,3 +16,9 @@
 [submodule "submodules/libyang"]
 	path = submodules/libyang
 	url = ../../github/CESNET/libyang
+[submodule "submodules/sysrepo"]
+	path = submodules/sysrepo
+	url = ../../github/sysrepo/sysrepo
+[submodule "submodules/libredblack"]
+	path = submodules/libredblack
+	url = ../../github/sysrepo/libredblack