https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=795eb42e060039b6d624b7e613d8c334ac70580c

commit 795eb42e060039b6d624b7e613d8c334ac70580c
Author: Zack Weinberg <zackw@panix.com>
Date:   Sat Mar 9 21:18:56 2019 -0500

    Don’t conditionalize declarations of ldiv_t, lldiv_t, __gwchar_t.
    
    The declarations of ldiv_t, lldiv_t, and __gwchar_t are all wrapped in
    __foo_t_defined conditionals, despite there being only one header in
    glibc that declares them.  I checked codesearch.debian.net and only
    found one other program that refers to the __foo_t_defined
    conditionals: u-boot provides its own definition of ldiv_t if
    __ldiv_t_defined is not defined by stdlib.h.  I conclude that the
    conditionals are not necessary, but the definitions of
    __ldiv_t_defined and __lldiv_t_defined should be preserved.
    
    	* stdlib/inttypes.h: Unconditionally define __gwchar_t.
            Don’t define ____gwchar_t_defined.
            * stdlib/stdlib.h: Unconditionally define ldiv_t.
            Condition lldiv_t only on __USE_ISOC99.

Diff:
---
 stdlib/inttypes.h | 15 ++++++---------
 stdlib/stdlib.h   |  6 ++----
 2 files changed, 8 insertions(+), 13 deletions(-)

diff --git a/stdlib/inttypes.h b/stdlib/inttypes.h
index 685dfc1..c5ec307 100644
--- a/stdlib/inttypes.h
+++ b/stdlib/inttypes.h
@@ -27,17 +27,14 @@
 #include <stdint.h>
 
 /* Get a definition for wchar_t.  But we must not define wchar_t itself.  */
-#ifndef ____gwchar_t_defined
-# ifdef __cplusplus
-#  define __gwchar_t wchar_t
-# elif defined __WCHAR_TYPE__
+#ifdef __cplusplus
+# define __gwchar_t wchar_t
+#elif defined __WCHAR_TYPE__
 typedef __WCHAR_TYPE__ __gwchar_t;
-# else
-#  define __need_wchar_t
-#  include <stddef.h>
+#else
+# define __need_wchar_t
+# include <stddef.h>
 typedef wchar_t __gwchar_t;
-# endif
-# define ____gwchar_t_defined	1
 #endif
 
 # if __WORDSIZE == 64
diff --git a/stdlib/stdlib.h b/stdlib/stdlib.h
index e347063..9f1f1b8 100644
--- a/stdlib/stdlib.h
+++ b/stdlib/stdlib.h
@@ -62,16 +62,14 @@ typedef struct
   } div_t;
 
 /* Returned by `ldiv'.  */
-#ifndef __ldiv_t_defined
 typedef struct
   {
     long int quot;		/* Quotient.  */
     long int rem;		/* Remainder.  */
   } ldiv_t;
-# define __ldiv_t_defined	1
-#endif
+#define __ldiv_t_defined	1
 
-#if defined __USE_ISOC99 && !defined __lldiv_t_defined
+#if defined __USE_ISOC99
 /* Returned by `lldiv'.  */
 __extension__ typedef struct
   {