imgconvert-test: skip pix formats without name

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

libavcodec/imgconvert.c

@@ -637,7 +637,7 @@ int main(void){
 
     for (i=0; i<AV_PIX_FMT_NB*2; i++) {
         AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(i);
-        if(!desc)
+        if(!desc || !desc->name)
             continue;
         av_log(0, AV_LOG_INFO, "pix fmt %s yuv_plan:%d avg_bpp:%d colortype:%d\n", desc->name, is_yuv_planar(desc), av_get_padded_bits_per_pixel(desc), get_color_type(desc));
         if ((!(desc->flags & PIX_FMT_ALPHA)) != (desc->nb_components != 2 && desc->nb_components != 4)) {