This ought to be built in in stdio, but it isn't.
Some s- files override this because their stdio internals differ. */
#ifdef __GNU_LIBRARY__
+/* The s- file might have overridden the definition with one that works for
+ the system's C library. But we are using the GNU C library, so this is
+ the right definition for every system. */
#undef PENDING_OUTPUT_COUNT
#define PENDING_OUTPUT_COUNT(FILE) ((FILE)->__bufp - (FILE)->__buffer)
#else