cosmetics: normalize include guards

use the recommended format [1] of:
<PROJECT>_<PATH>_<FILE>_H_

[1] https://google.github.io/styleguide/cppguide.html#The__define_Guard
"All header files should have #define guards to prevent multiple
inclusion. The format of the symbol name should be
<PROJECT>_<PATH>_<FILE>_H_."

Change-Id: I00a0595fc2a5fc736ab6ff3215727d6db05b10e1
diff --git a/av1/encoder/corner_match.h b/av1/encoder/corner_match.h
index 3b16f9e..535d2fa 100644
--- a/av1/encoder/corner_match.h
+++ b/av1/encoder/corner_match.h
@@ -8,8 +8,8 @@
  * Media Patent License 1.0 was not distributed with this source code in the
  * PATENTS file, you can obtain it at www.aomedia.org/license/patent.
  */
-#ifndef AV1_ENCODER_CORNER_MATCH_H_
-#define AV1_ENCODER_CORNER_MATCH_H_
+#ifndef AOM_AV1_ENCODER_CORNER_MATCH_H_
+#define AOM_AV1_ENCODER_CORNER_MATCH_H_
 
 #include <stdio.h>
 #include <stdlib.h>
@@ -30,4 +30,4 @@
                              int height, int frm_stride, int ref_stride,
                              int *correspondence_pts);
 
-#endif  // AV1_ENCODER_CORNER_MATCH_H_
+#endif  // AOM_AV1_ENCODER_CORNER_MATCH_H_