fftools/ffprobe: Use av_err2str

av_err2str which is a wrapper for av_strerror already calls
strerror_r if available and if not has a fallback for the other
error codes that would be handled by that, so manually calling
strerror again if it fails is not necessary.

Signed-off-by: Anton Khirnov <anton@khirnov.net>

fftools/ffprobe.c

@@ -3279,15 +3279,9 @@ static int show_format(WriterContext *w, InputFile *ifile)
 
 static void show_error(WriterContext *w, int err)
 {
-    char errbuf[128];
-    const char *errbuf_ptr = errbuf;
-
-    if (av_strerror(err, errbuf, sizeof(errbuf)) < 0)
-        errbuf_ptr = strerror(AVUNERROR(err));
-
     writer_print_section_header(w, SECTION_ID_ERROR);
     print_int("code", err);
-    print_str("string", errbuf_ptr);
+    print_str("string", av_err2str(err));
     writer_print_section_footer(w);
 }