Remove NO_DIRENT; it isn't used anywhere

Reviewed-by: NRichard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4261)

e_os.h

@@ -147,7 +147,6 @@ extern "C" {
 #  if !defined(WINNT) && !defined(__DJGPP__)
 #   define NO_SYSLOG
 #  endif
-#  define NO_DIRENT
 
 #  ifdef WINDOWS
 #   if !defined(_WIN32_WCE) && !defined(_WIN32_WINNT)