Signal color-range in Y4M output

Only set if the color-range is full.

BUG=aomedia:2876

Change-Id: I3882bcbc7440f83a99268292531557c2859e3522
diff --git a/common/y4menc.h b/common/y4menc.h
index f6d5fd8..6484efc 100644
--- a/common/y4menc.h
+++ b/common/y4menc.h
@@ -20,12 +20,12 @@
 extern "C" {
 #endif
 
-#define Y4M_BUFFER_SIZE 128
+#define Y4M_BUFFER_SIZE 256
 
 int y4m_write_file_header(char *buf, size_t len, int width, int height,
                           const struct AvxRational *framerate, int monochrome,
                           aom_chroma_sample_position_t csp, aom_img_fmt_t fmt,
-                          unsigned int bit_depth);
+                          unsigned int bit_depth, aom_color_range_t range);
 int y4m_write_frame_header(char *buf, size_t len);
 void y4m_write_image_file(const aom_image_t *img, const int *planes,
                           FILE *file);