strftime() was in C89 so use it unconditionally.

config.h.in

@@ -654,9 +654,6 @@
 /* Define to 1 if you have the <stdlib.h> header file. */
 #undef HAVE_STDLIB_H
 
-/* Define to 1 if you have the `strftime' function. */
-#undef HAVE_STRFTIME
-
 /* Define to 1 if you have the <strings.h> header file. */
 #undef HAVE_STRINGS_H
 

configure

@@ -2847,7 +2847,6 @@ as_fn_append ac_header_list " sys/sysmacros.h"
 as_fn_append ac_func_list " fexecve"
 as_fn_append ac_func_list " killpg"
 as_fn_append ac_func_list " nl_langinfo"
-as_fn_append ac_func_list " strftime"
 as_fn_append ac_func_list " pread"
 as_fn_append ac_func_list " pwrite"
 as_fn_append ac_func_list " openat"
@@ -18692,8 +18691,6 @@ done
 
 
 
-
-
 case "$host_os" in
     hpux*)
 	if test X"$ac_cv_func_pread" = X"yes"; then

configure.ac

@@ -2394,7 +2394,7 @@ dnl
 dnl Function checks
 dnl
 AC_FUNC_GETGROUPS
-AC_CHECK_FUNCS_ONCE([fexecve killpg nl_langinfo strftime pread pwrite openat faccessat wordexp])
+AC_CHECK_FUNCS_ONCE([fexecve killpg nl_langinfo pread pwrite openat faccessat wordexp])
 case "$host_os" in
     hpux*)
 	if test X"$ac_cv_func_pread" = X"yes"; then

plugins/sudoers/timestr.c

@@ -28,13 +28,10 @@
 
 /*
  * Return a static buffer with the current date + time.
- * Uses strftime() if available, else falls back to ctime().
  */
 char *
 get_timestr(time_t tstamp, int log_year)
 {
-    char *s;
-#ifdef HAVE_STRFTIME
     static char buf[128];
     struct tm *timeptr;
 
@@ -45,17 +42,5 @@ get_timestr(time_t tstamp, int log_year)
 	    timeptr) != 0 && buf[sizeof(buf) - 1] == '\0')
 	    return buf;
     }
-
-#endif /* HAVE_STRFTIME */
-
-    s = ctime(&tstamp);
-    if (s != NULL) {
-	s += 4;				/* skip day of the week */
-	if (log_year)
-	    s[20] = '\0';		/* avoid the newline */
-	else
-	    s[15] = '\0';		/* don't care about year */
-    }
-
-    return s;
+    return NULL;
 }