sync for stddef.h

[Note: keeping the *_FILENO macros defined in apr-1.x]


apr_general: Use __builtin_offsetof for APR_OFFSETOF if available.  PR 68763.

Sanitizers might warn about &((type *)0)->field being UB, so use the builtin
which is meant to avoid it.


Merges r892156, r1916337 ^/apr/apr/trunk
Submitted by: wrowe, ylavic


git-svn-id: https://svn.apache.org/repos/asf/apr/apr/branches/1.8.x@1916338 13f79535-47bb-0310-9956-ffa450edef68

configure.in

@@ -1804,6 +1804,7 @@ AC_SUBST(netinet_sctph)
 AC_SUBST(netinet_sctp_uioh)
 AC_SUBST(netinet_tcph)
 AC_SUBST(stdargh)
+AC_SUBST(stddefh)
 AC_SUBST(stdioh)
 AC_SUBST(stdlibh)
 AC_SUBST(stringh)

include/apr.h.in

@@ -88,6 +88,7 @@
 #define APR_HAVE_SEMAPHORE_H     @semaphoreh@
 #define APR_HAVE_SIGNAL_H        @signalh@
 #define APR_HAVE_STDARG_H        @stdargh@
+#define APR_HAVE_STDDEF_H        @stddefh@
 #define APR_HAVE_STDINT_H        @stdint@
 #define APR_HAVE_STDIO_H         @stdioh@
 #define APR_HAVE_STDLIB_H        @stdlibh@
@@ -165,6 +166,10 @@
 #include <sys/types.h>
 #endif
 
+#if APR_HAVE_STDDEF_H
+#include <stddef.h>
+#endif
+
 #if APR_HAVE_SYS_SOCKET_H
 #include <sys/socket.h>
 #endif

include/apr_general.h

@@ -103,7 +103,9 @@ typedef int               apr_signum_t;
  * @param field  data field within the structure
  * @return offset
  */
-#if defined(offsetof) && !defined(__cplusplus)
+#if defined(__has_builtin) && __has_builtin(__builtin_offsetof)
+#define APR_OFFSETOF(s_type,field) __builtin_offsetof(s_type,field)
+#elif defined(offsetof) && !defined(__cplusplus)
 #define APR_OFFSETOF(s_type,field) offsetof(s_type,field)
 #else
 #define APR_OFFSETOF(s_type,field) APR_OFFSET(s_type*,field)