stubdom: fix "make build"

Cross compiling libxc requires some symlinks to exist.

Note that make -C tools/include requires running tools/configure. But at
least now the error message is much better than just a "file not found"
error.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Ian Jakcson <ian.jackson@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Samuel Thibault <samuel.thibault@ens-lyon.org>

stubdom/Makefile

@@ -333,6 +333,8 @@ $(TARGETS_MINIOS): mini-os-%:
 .PHONY: libxc
 libxc: libxc-$(XEN_TARGET_ARCH)/libxenctrl.a libxc-$(XEN_TARGET_ARCH)/libxenguest.a
 libxc-$(XEN_TARGET_ARCH)/libxenctrl.a: cross-zlib
+	$(MAKE) -C $(XEN_ROOT)/tools/include
+	$(MAKE) DESTDIR= -C $(MINI_OS) links
 	CPPFLAGS="$(TARGET_CPPFLAGS)" CFLAGS="$(TARGET_CFLAGS)" $(MAKE) DESTDIR= CONFIG_LIBXC_MINIOS=y -C libxc-$(XEN_TARGET_ARCH)
 
  libxc-$(XEN_TARGET_ARCH)/libxenguest.a: libxc-$(XEN_TARGET_ARCH)/libxenctrl.a