Avoid hardcoding runpath

--- nmap-7.80/libdnet-stripped/src/Makefile.in.1	2020-07-30 16:57:20.017444924 +0000
+++ nmap-7.80/libdnet-stripped/src/Makefile.in	2020-07-30 16:57:34.443645475 +0000
@@ -265,7 +265,7 @@
 	  rm -f "$${dir}/so_locations"; \
 	done
 libdnet.la: $(libdnet_la_OBJECTS) $(libdnet_la_DEPENDENCIES) 
-	$(libdnet_la_LINK) -rpath $(libdir) $(libdnet_la_OBJECTS) $(libdnet_la_LIBADD) $(LIBS)
+	$(libdnet_la_LINK) $(libdnet_la_OBJECTS) $(libdnet_la_LIBADD) $(LIBS)
 
 mostlyclean-compile:
 	-rm -f *.$(OBJEXT)