bit_depth_template: Use file name as multiple inclusion guard

libavcodec/bit_depth_template.c

@@ -22,7 +22,7 @@
 #define BIT_DEPTH 8
 #endif
 
-#ifdef AVCODEC_H264_HIGH_DEPTH_H
+#ifdef AVCODEC_BIT_DEPTH_TEMPLATE_C
 #   undef pixel
 #   undef pixel2
 #   undef pixel4
@@ -42,7 +42,7 @@
 #   undef av_clip_pixel
 #   undef PIXEL_SPLAT_X4
 #else
-#   define AVCODEC_H264_HIGH_DEPTH_H
+#   define AVCODEC_BIT_DEPTH_TEMPLATE_C
 #endif
 
 #if BIT_DEPTH > 8