imagebuilder: run build prereq checks before building image to set up host commands properly

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

SVN-Revision: 46840

target/imagebuilder/files/Makefile

@@ -85,6 +85,21 @@ endef
 
 include $(INCLUDE_DIR)/target.mk
 
+staging_dir/host/.prereq-build: include/prereq-build.mk
+	mkdir -p tmp
+	rm -f tmp/.host.mk
+	@$(_SINGLE)$(NO_TRACE_MAKE) -j1 -r -s -f $(TOPDIR)/include/prereq-build.mk prereq 2>/dev/null || { \
+		echo "Prerequisite check failed. Use FORCE=1 to override."; \
+		false; \
+	}
+  ifneq ($(realpath $(TOPDIR)/include/prepare.mk),)
+	@$(_SINGLE)$(NO_TRACE_MAKE) -j1 -r -s -f $(TOPDIR)/include/prepare.mk prepare 2>/dev/null || { \
+		echo "Preparation failed."; \
+		false; \
+	}
+  endif
+	touch $@
+
 _call_info: FORCE
 	echo 'Current Target: "$(BOARD)$(if $(SUBTARGET), ($(BOARDNAME)))"'
 	echo 'Default Packages: $(DEFAULT_PACKAGES)'
@@ -96,7 +111,7 @@ BUILD_PACKAGES:=$(sort $(DEFAULT_PACKAGES) $(USER_PACKAGES) $($(USER_PROFILE)_PA
 BUILD_PACKAGES:=$(filter-out $(filter -%,$(BUILD_PACKAGES)) $(patsubst -%,%,$(filter -%,$(BUILD_PACKAGES))),$(BUILD_PACKAGES))
 PACKAGES:=
 
-_call_image:
+_call_image: staging_dir/host/.prereq-build
 	echo 'Building images for $(BOARD)$(if $($(USER_PROFILE)_NAME), - $($(USER_PROFILE)_NAME))'
 	echo 'Packages: $(BUILD_PACKAGES)'
 	echo