avutil/opencl: fix a segmentfault in libavutil/opencl.c

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavutil/opencl.c

@@ -169,7 +169,7 @@ static const OpenclErrorMsg opencl_err_msg[] = {
 const char *av_opencl_errstr(cl_int status)
 {
     int i;
-    for (i = 0; i < sizeof(opencl_err_msg); i++) {
+    for (i = 0; i < FF_ARRAY_ELEMS(opencl_err_msg); i++) {
         if (opencl_err_msg[i].err_code == status)
             return opencl_err_msg[i].err_str;
     }