update osm2pgsql (empty waterways)

fixes #153

diff --git a/osm2pgsql b/osm2pgsql
index b59765e3ac591ff84f21f4a1153e7c18a2d2b855..13c11f8842146a79cb0629b603e5acdfbb0bfd58 160000 (submodule)
--- a/osm2pgsql
+++ b/osm2pgsql
@@ -1 +1 @@
-Subproject commit b59765e3ac591ff84f21f4a1153e7c18a2d2b855
+Subproject commit 13c11f8842146a79cb0629b603e5acdfbb0bfd58