revert to osm2pgsql 1.8.1

diff --git a/osm2pgsql b/osm2pgsql
index ea0178e97d5b69a87a8b9c35210c8be4674e60e6..8e5bf4b2ceba46167f3380206ed36c380682c485 160000 (submodule)
--- a/osm2pgsql
+++ b/osm2pgsql
@@ -1 +1 @@
-Subproject commit ea0178e97d5b69a87a8b9c35210c8be4674e60e6
+Subproject commit 8e5bf4b2ceba46167f3380206ed36c380682c485