Replace '#ifdef CONFIG_...' with '#if CONFIG_...'

This affects two places:
* Fixes a compile error with frame-superres when
  highbitdepth is disabled.
* Avoids including some supertx-related code when supertx
  is disabled

BUG=aomedia:602

Change-Id: Idfc478fd88ade91d48c93cfd8abdd2bea86de898
diff --git a/av1/common/resize.c b/av1/common/resize.c
index b5db615..322b593 100644
--- a/av1/common/resize.c
+++ b/av1/common/resize.c
@@ -902,7 +902,7 @@
 
   if (aom_alloc_frame_buffer(&copy_buffer, cm->width, cm->height,
                              cm->subsampling_x, cm->subsampling_y,
-#ifdef CONFIG_HIGHBITDEPTH
+#if CONFIG_HIGHBITDEPTH
                              cm->use_highbitdepth,
 #endif  // CONFIG_HIGHBITDEPTH
                              AOM_BORDER_IN_PIXELS, cm->byte_alignment))
@@ -933,7 +933,7 @@
     if (aom_realloc_frame_buffer(
             frame_to_show, cm->superres_upscaled_width,
             cm->superres_upscaled_height, cm->subsampling_x, cm->subsampling_y,
-#ifdef CONFIG_HIGHBITDEPTH
+#if CONFIG_HIGHBITDEPTH
             cm->use_highbitdepth,
 #endif  // CONFIG_HIGHBITDEPTH
             AOM_BORDER_IN_PIXELS, cm->byte_alignment, fb, cb, cb_priv))
@@ -945,7 +945,7 @@
     if (aom_alloc_frame_buffer(frame_to_show, cm->superres_upscaled_width,
                                cm->superres_upscaled_height, cm->subsampling_x,
                                cm->subsampling_y,
-#ifdef CONFIG_HIGHBITDEPTH
+#if CONFIG_HIGHBITDEPTH
                                cm->use_highbitdepth,
 #endif  // CONFIG_HIGHBITDEPTH
                                AOM_BORDER_IN_PIXELS, cm->byte_alignment))