update osm2pgsql to current master (fixes version output)

diff --git a/osm2pgsql b/osm2pgsql
index 497476d56f7c1fcbbdb95b363293de6ce0feac00..7869a4e1255a7657bc8582a58adcf5aa2a3f3c70 160000 (submodule)
--- a/osm2pgsql
+++ b/osm2pgsql
@@ -1 +1 @@
-Subproject commit 497476d56f7c1fcbbdb95b363293de6ce0feac00
+Subproject commit 7869a4e1255a7657bc8582a58adcf5aa2a3f3c70