Print a message before executing the post-build script

Signed-off-by: Luca Ceresoli <luca@lucaceresoli.net>
Acked-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

Makefile

@@ -486,6 +486,7 @@ endif
 	) >  $(TARGET_DIR)/etc/os-release
 
 ifneq ($(BR2_ROOTFS_POST_BUILD_SCRIPT),"")
+	@$(call MESSAGE,"Executing post-build script")
 	$(BR2_ROOTFS_POST_BUILD_SCRIPT) $(TARGET_DIR)
 endif