Generalizer bugfix: Set delete_existing earlier

In append mode we need to delete existing tiles. We need to set this
parameter earlier, so the generalizer is initialized correctly.

Author: joto

src/gen/osm2pgsql-gen.cpp

@@ -317,6 +317,10 @@ class genproc_t
             params.set("schema", m_dbschema);
         }
 
+        if (m_append) {
+            params.set("delete_existing", true);
+        }
+
         write_to_debug_log(params, "Params (config):");
 
         log_debug("Connecting to database...");
@@ -329,10 +333,6 @@ class genproc_t
         log_info("Running generalizer '{}' ({})...", generalizer->name(),
                  generalizer->strategy());
 
-        if (m_append) {
-            params.set("delete_existing", true);
-        }
-
         write_to_debug_log(params, "Params (after initialization):");
 
         util::timer_t timer_gen;