Makefile: require libmxml.a for its installation

Signed-off-by: Richard Leitner <richard.leitner@skidata.com>

Makefile.in

@@ -162,7 +162,7 @@ install:	$(TARGETS) install-$(LIBMXML) install-libmxml.a
 	$(INSTALL_DIR) $(BUILDROOT)$(mandir)/man3
 	$(INSTALL_MAN) doc/mxml.man $(BUILDROOT)$(mandir)/man3/mxml.3
 
-install-libmxml.a:
+install-libmxml.a: libmxml.a
 	echo Installing libmxml.a to $(BUILDROOT)$(libdir)...
 	$(INSTALL_DIR) $(BUILDROOT)$(libdir)
 	$(INSTALL_LIB) libmxml.a $(BUILDROOT)$(libdir)