Fix compilation with glibc-2.28.
https://bugs.gentoo.org/681904

--- emacs-18.59-orig/src/ChangeLog
+++ emacs-18.59/src/ChangeLog
@@ -1,3 +1,9 @@
+2019-08-29  Ulrich Mueller  <ulm@gentoo.org>
+
+	* s-linux.h (PENDING_OUTPUT_COUNT): Fix conditional for new
+	C libio names. This was wrong since a long time, but finally broke
+	when glibc-2.28 dropped libio.h.
+
 2018-07-01  Ulrich Mueller  <ulm@gentoo.org>
 
 	* x11term.c (x_init_1): Save the O_NONBLOCK bit, so that it won't
--- emacs-18.59-orig/src/s-linux.h
+++ emacs-18.59/src/s-linux.h
@@ -230,7 +230,8 @@
 /* we have non-standard standard I/O (iostream) ... */
 #ifdef emacs
 #include <stdio.h>  /* Get the definition of _IO_STDIO_H.  */
-#if defined(_IO_STDIO_H) || defined(_STDIO_USES_IOSTREAM)
+#if defined(_IO_STDIO_H) || defined(_STDIO_USES_IOSTREAM) \
+    || defined _IO_EOF_SEEN || __GNU_LIBRARY__ == 1
 /* new C libio names */
 #define PENDING_OUTPUT_COUNT(FILE) \
   ((FILE)->_IO_write_ptr - (FILE)->_IO_write_base)