The Doctor reported triggering an assertion in convert_file_to(), due
to an unexpected errno from iconv(). According to the comments, the
assertions were only enabled for debugging and should have been turned
off. We certainly don't want to abort mutt for this case, so just
disable them as the comment indicates.
#endif
/* If you are debugging this file, comment out the following line. */
-/*#define NDEBUG*/
+#define NDEBUG
#ifdef NDEBUG
#define assert(x)