$NetBSD$

Improvement for build system
--- Makefile.mk.orig	2007-01-27 18:43:39.000000000 +0200
+++ Makefile.mk
@@ -94,4 +94,6 @@ links:
 	else \
 		sh build/crossln $(ROOT)$(MANDIR)/man1/oawk.1 $(ROOT)$(MANDIR)/man1/awk.1 $(ROOT); \
 	fi
-	$(SHELL) build/maninst -c -m 644 intro.1 $(ROOT)$(MANDIR)/man1/intro.1
+	if test -z "${NO_INSTALL_INTRO}"; then \
+		$(SHELL) build/maninst -c -m 644 intro.1 $(ROOT)$(MANDIR)/man1/intro.1; \
+	fi
