minc: extract DT_* handling

minc.c

@@ -11,6 +11,7 @@
 #include <unistd.h>
 
 #include "blaze822.h"
+#include "blaze822_priv.h"
 
 static int qflag;
 static int status;
@@ -35,10 +36,9 @@ inc(char *dir)
 	}
 
 	while ((d = readdir(fd))) {
-#if defined(DT_REG) && defined(DT_UNKNOWN)
-		if (d->d_type != DT_REG && d->d_type != DT_UNKNOWN)
+		if (!MAIL_DT(d->d_type))
 			continue;
-#endif
+
 		if (d->d_name[0] == '.')
 			continue;