configure osm2pgsql and module location via cmake

The default location of osm2pgsql and the postgresql module
is decided at compile/installation time and is not necessarily
in the project directory.

With this change it is now possible to have a project directory
that is completely separate from the build directory.

lib/setup_functions.php

@@ -17,12 +17,7 @@ function checkInFile($sOSMFile)
 
 function getOsm2pgsqlBinary()
 {
-    $sBinary = getSetting('OSM2PGSQL_BINARY');
-    if (!$sBinary) {
-        $sBinary = CONST_InstallDir.'/osm2pgsql/osm2pgsql';
-    }
-
-    return $sBinary;
+    return getSetting('OSM2PGSQL_BINARY', CONST_Default_Osm2pgsql);
 }
 
 function getImportStyle()