Add a flag to manually override VABC

Test: generate an OTA with --disable_vabc
Change-Id: I4a42319584dc1388d097dba343fe3ace82479bec
diff --git a/payload_generator/payload_file.cc b/payload_generator/payload_file.cc
index 33c0749..1174597 100644
--- a/payload_generator/payload_file.cc
+++ b/payload_generator/payload_file.cc
@@ -71,6 +71,9 @@
     *(manifest_.mutable_dynamic_partition_metadata()) =
         *(config.target.dynamic_partition_metadata);
 
+  if (config.disable_vabc) {
+    manifest_.mutable_dynamic_partition_metadata()->set_vabc_enabled(false);
+  }
   if (config.is_partial_update) {
     manifest_.set_partial_update(true);
   }