FreeBSD 11: Fix clang (v6) builds

While CDE builds fine with gcc6 on FreeBSD 11, the default clang build
was broken in a few places.  This commit allows CDE to build now using
the default clang 6 system compiler.

cde/programs/dtmail/libDtMail/Common/FileShare.C

@@ -353,7 +353,7 @@ FileShare::lockFile(DtMailEnv & error)
 	if (isModified(error) == DTM_FALSE) {
 	  break;
 	} else {
-	  if (time((time_t)NULL) - t_start > FileShareTimeout) {
+	  if (time(NULL) - t_start > FileShareTimeout) {
 	    // time out!
 	    error.setError(DTME_OtherOwnsWrite);
 	    return;