Generate messages first, then check submodules

Makefile

@@ -124,7 +124,7 @@ $(STAGED_FIRMWARES): $(IMAGE_DIR)%.px4: $(BUILD_DIR)%.build/firmware.px4
 .PHONY: $(FIRMWARES)
 $(BUILD_DIR)%.build/firmware.px4: config   = $(patsubst $(BUILD_DIR)%.build/firmware.px4,%,$@)
 $(BUILD_DIR)%.build/firmware.px4: work_dir = $(BUILD_DIR)$(config).build/
-$(FIRMWARES): $(BUILD_DIR)%.build/firmware.px4:	checksubmodules generateuorbtopicheaders
+$(FIRMWARES): $(BUILD_DIR)%.build/firmware.px4:	generateuorbtopicheaders checksubmodules
 	@$(ECHO) %%%%
 	@$(ECHO) %%%% Building $(config) in $(work_dir)
 	@$(ECHO) %%%%