install hlr.sql in prefix/doc/osmo-hlr/

In particular I need this to start a fresh osmo-hlr instance on the
osmo-gsm-tester. Might also come in handy during packaging?

Change-Id: I08e48375814ab93691892299d34909c6d0bf12a2
diff --git a/debian/osmo-hlr.install b/debian/osmo-hlr.install
index 028b9b3..114df0b 100644
--- a/debian/osmo-hlr.install
+++ b/debian/osmo-hlr.install
@@ -1 +1,2 @@
 /usr/bin/osmo-hlr
+/usr/share/doc/osmo-hlr/hlr.sql