Patch: incomplete 'make clean' in liblunicode (ITS#1791)

In liblunicode, 'make clean' and 'make distclean' do not remove
the symlinks ucdata.h and ure.h.

from Hallvard B. Furuseth <h.b.furuseth@usit.uio.no>

libraries/liblunicode/Makefile.in

@@ -42,6 +42,6 @@ install-local: $(PROGRAMS) FORCE
 $(XXSRCS) : .links
 
 clean-local: FORCE
-	@$(RM) *.dat .links
+	@$(RM) *.dat .links $(XXHEADERS)
 
 depend-common: .links