Avoid use of an uninitialized variable

DefaultConfig() uses set_scale_mode_, so this comit move the call to
before after set_scale_mode_ is set.

BUG=aomedia:2744

Change-Id: I3dae3f559af9e83c6ea0ff8702ba559da9385434
diff --git a/test/resize_test.cc b/test/resize_test.cc
index 3fa3d83..468027e 100644
--- a/test/resize_test.cc
+++ b/test/resize_test.cc
@@ -533,12 +533,12 @@
 TEST_P(ResizeRealtimeTest, TestExternalResizeWorks) {
   ResizingVideoSource video;
   video.flag_codec_ = 1;
-  DefaultConfig();
   change_bitrate_ = false;
   set_scale_mode_ = false;
   set_scale_mode2_ = false;
   mismatch_psnr_ = 0.0;
   mismatch_nframes_ = 0;
+  DefaultConfig();
   ASSERT_NO_FATAL_FAILURE(RunLoop(&video));
 
   // Check we decoded the same number of frames as we attempted to encode