sql/Makefile: Create empty /var/lib/osmocom directory at install time

Otherwise osmo-hlr is unable to start correctly.

Change-Id: I1233fc9b3dc685561f79a34e1c32c459dc1aa685
diff --git a/debian/osmo-hlr.install b/debian/osmo-hlr.install
index 825e65c..7991522 100644
--- a/debian/osmo-hlr.install
+++ b/debian/osmo-hlr.install
@@ -3,3 +3,4 @@
 /usr/share/doc/osmo-hlr/sql/hlr.sql
 /usr/share/doc/osmo-hlr/sql/hlr_data.sql
 /usr/share/doc/osmo-hlr/examples/osmo-hlr.cfg
+/var/lib/osmocom