expat: add host build

mesa in the video feed requires expat/host. Provide host build to
allow mesa to build.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

libs/expat/Makefile

@@ -21,6 +21,7 @@ PKG_CPE_ID:=cpe:/a:libexpat:expat
 CMAKE_INSTALL:=1
 
 include $(INCLUDE_DIR)/package.mk
+include $(INCLUDE_DIR)/host-build.mk
 include $(INCLUDE_DIR)/cmake.mk
 
 define Package/libexpat
@@ -51,4 +52,5 @@ define Package/libexpat/install
 	$(CP) $(PKG_INSTALL_DIR)/usr/lib/libexpat.so.* $(1)/usr/lib/
 endef
 
+$(eval $(call HostBuild))
 $(eval $(call BuildPackage,libexpat))