exclude config.{sub,guess} from source package

Lintian complains about these links in the source package as they leave
the source directory and as they are autogenerated there isn't that much
sense in shipping them, we can just recreate them before calling
configure.

debian/rules

@@ -77,7 +77,7 @@ build/environment.mak: build/configure-stamp
 	@true
 
 configure: configure.ac
-build/configure-stamp: configure
+build/configure-stamp: configure buildlib/config.sub buildlib/config.guess
 	dh_testdir
 	-mkdir build
 	cp COPYING debian/copyright
@@ -116,6 +116,8 @@ clean:
 	rm -rf build
 	rm -f debian/$(LIBAPT_PKG).install debian/$(LIBAPT_INST).install \
 	      debian/libapt-pkg-dev.install
+	test ! -L buildlib/config.guess || rm -f buildlib/config.guess
+	test ! -L buildlib/config.sub || rm -f buildlib/config.sub
 
 debian/%.install: debian/%.install.in
 	sed 's/@DEB_HOST_MULTIARCH@/$(DEB_HOST_MULTIARCH)/g' $< > $@
@@ -328,6 +330,9 @@ apt-transport-https: build-binary libapt-pkg-dev
 	dh_md5sums -p$@
 	dh_builddeb -p$@
 
+buildlib/config.guess buildlib/config.sub:
+	$(MAKE) "$@"
+
 configure:
 	$(MAKE) configure