doc/examples/vaapi_encode: open raw YUV input in binary mode

fopen() with "r" opens the file in text mode, which on Windows
translates \r\n to \n, corrupting raw NV12 pixel data. Use "rb"
to open in binary mode, matching the output file which already
uses "w+b".

Signed-off-by: Jun Zhao <barryjzhao@tencent.com>

doc/examples/vaapi_encode.c

@@ -118,7 +118,7 @@ int main(int argc, char *argv[])
     height = atoi(argv[2]);
     size   = width * height;
 
-    if (!(fin = fopen(argv[3], "r"))) {
+    if (!(fin = fopen(argv[3], "rb"))) {
         fprintf(stderr, "Fail to open input file : %s\n", strerror(errno));
         return -1;
     }