plug-ins: fix a crash in tiff_io_error().

I had a TIFF file which would crash while triggering an error, inside g_logv()
code (and according to the stacktrace, even probably inside some lower level
printf implementation code).

The reason was that I already processed the variable list with
g_strdup_vprintf() and printf didn't like this va_list being reused, then
segfaulted with some "Cannot access memory at address" error.

The alternate fix was to first copy the va_list in the first use with
va_copy()/G_VA_COPY, yet since we already processed the format data, I thought
it was useless to do this. Let's just directly use the formatted string.

(cherry picked from commit fb1f16d4b8)

plug-ins/file-tiff/file-tiff-io.c

@@ -282,32 +282,29 @@ tiff_io_error (const gchar *module,
                const gchar *fmt,
                va_list      ap)
 {
+  gchar *msg;
+
   /* Workaround for: http://bugzilla.gnome.org/show_bug.cgi?id=132297
    * Ignore the errors related to random access and JPEG compression
    */
   if (! strcmp (fmt, "Compression algorithm does not support random access"))
     return;
 
+  msg = g_strdup_vprintf (fmt, ap);
+
 #ifdef TIFF_VERSION_BIG
   if (g_strcmp0 (fmt, "Maximum TIFF file size exceeded") == 0)
-    {
     /* @module in my tests were "TIFFAppendToStrip" but I wonder if
      * this same error could not happen with other "modules".
      */
     tiff_file_size_error = TRUE;
-    }
   else
-    {
+    /* Easier for debugging to at least print messages on stderr. */
-      gchar *msg = g_strdup_vprintf (fmt, ap);
-
-      /* Easier for debugging to at least print messages on stderr; */
     g_printerr ("LibTiff error: [%s] %s\n", module, msg);
-      g_free (msg);
-    }
-
 #endif
 
-  g_logv (G_LOG_DOMAIN, G_LOG_LEVEL_MESSAGE, fmt, ap);
+  g_log (G_LOG_DOMAIN, G_LOG_LEVEL_MESSAGE, "%s", msg);
+  g_free (msg);
 }
 
 static tsize_t