git clean is a better way to clean the tree.

hack.mk

@@ -1,4 +0,0 @@
-clean:
-	find . -name \*~ -print0 | xargs -0 rm
-	find . -name \*.in -print0 | xargs -0 rm
-	rm -rf aclocal.m4 autom4te.cache compile config.* configure depcomp install-sh missing btpd-*.tar.gz