update osm2pgsql to 1.5.1

diff --git a/osm2pgsql b/osm2pgsql
index 7869a4e1255a7657bc8582a58adcf5aa2a3f3c70..bd7b4440000a9c1df639c5fac020bc00bd590368 160000 (submodule)
--- a/osm2pgsql
+++ b/osm2pgsql
@@ -1 +1 @@
-Subproject commit 7869a4e1255a7657bc8582a58adcf5aa2a3f3c70
+Subproject commit bd7b4440000a9c1df639c5fac020bc00bd590368