Define _TIME_BITS=64 on systems that define __TIMESIZE, like GNU libc.

This should be replaced by a specialized autoconf macro when one
becomes available.

config.h.in

@@ -1386,6 +1386,9 @@
 /* Define for large files, on AIX-style hosts. */
 #undef _LARGE_FILES
 
+/* Number of bits in a time_t, on hosts where this is settable. */
+#undef _TIME_BITS
+
 /* Define to __FUNCTION__ if your compiler supports __FUNCTION__ but not
    __func__ */
 #undef __func__

configure

@@ -19341,7 +19341,9 @@ fi
 
 done
 #
-# Check for large file support.
+# Check for large file and 64-bit time support.
+# GNU libc only allows setting _TIME_BITS when FILE_OFFSET_BITS is also set.
+# GNU libc defines __TIMESIZE on systems where _TIME_BITS can be set.
 #
 # Check whether --enable-largefile was given.
 if test ${enable_largefile+y}
@@ -19547,6 +19549,22 @@ rm -rf conftest*
   fi
 fi
 
+if test X"$ac_cv_sys_file_offset_bits" = X"yes"; then
+    ac_fn_check_decl "$LINENO" "__TIMESIZE" "ac_cv_have_decl___TIMESIZE" "
+$ac_includes_default
+#include <time.h>
+
+" "$ac_c_undeclared_builtin_options" "CFLAGS"
+if test "x$ac_cv_have_decl___TIMESIZE" = xyes
+then :
+
+
+printf "%s\n" "#define _TIME_BITS 64" >>confdefs.h
+
+
+fi
+fi
+
 #
 # HP-UX may need to define _XOPEN_SOURCE_EXTENDED to expose MSG_WAITALL.
 # Also, HP-UX 11.23 has a broken sys/types.h when large files support

configure.ac

@@ -2447,9 +2447,20 @@ AC_CHECK_HEADERS([procfs.h] [sys/procfs.h], [AC_CHECK_MEMBERS(struct psinfo.pr_t
 ])]
 break)
 #
-# Check for large file support.
+# Check for large file and 64-bit time support.
+# GNU libc only allows setting _TIME_BITS when FILE_OFFSET_BITS is also set.
+# GNU libc defines __TIMESIZE on systems where _TIME_BITS can be set.
 #
 AC_SYS_LARGEFILE
+if test X"$ac_cv_sys_file_offset_bits" = X"yes"; then
+    AC_CHECK_DECL(__TIMESIZE, [
+	AC_DEFINE([_TIME_BITS], [64], [Number of bits in a time_t, on hosts where this is settable.])
+    ], [], [
+AC_INCLUDES_DEFAULT
+#include <time.h>
+    ])
+fi
+
 #
 # HP-UX may need to define _XOPEN_SOURCE_EXTENDED to expose MSG_WAITALL.
 # Also, HP-UX 11.23 has a broken sys/types.h when large files support