infra: replace BUILDROOT_CONFIG with BR2_CONFIG

To make the naming consistent (all user-visible options should be
prefixed with BR2_).

An entry is added to Makefile.legacy to warn users who have set
BUILDROOT_CONFIG but not BR2_CONFIG.

Still export BUILDROOT_CONFIG but pointing to some phony value, to
make sure that scripts that still use it fail in a predictable way.

Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Tested-by: Jérémy Rosen <jeremy.rosen@openwide.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
diff --git a/Makefile b/Makefile
index 563fbfd..72b11b8 100644
--- a/Makefile
+++ b/Makefile
@@ -152,11 +152,11 @@
 LEGAL_WARNINGS=$(LEGAL_INFO_DIR)/.warnings
 LEGAL_REPORT=$(LEGAL_INFO_DIR)/README
 
-BUILDROOT_CONFIG=$(CONFIG_DIR)/.config
+BR2_CONFIG=$(CONFIG_DIR)/.config
 
 # Pull in the user's configuration file
 ifeq ($(filter $(noconfig_targets),$(MAKECMDGOALS)),)
--include $(BUILDROOT_CONFIG)
+-include $(BR2_CONFIG)
 endif
 
 # To put more focus on warnings, be less verbose as default
@@ -331,7 +331,7 @@
 
 # Scripts in support/ or post-build scripts may need to reference
 # these locations, so export them so it is easier to use
-export BUILDROOT_CONFIG
+export BR2_CONFIG
 export TARGET_DIR
 export STAGING_DIR
 export HOST_DIR
@@ -428,7 +428,7 @@
 dirs: $(BUILD_DIR) $(STAGING_DIR) $(TARGET_DIR) \
 	$(HOST_DIR) $(BINARIES_DIR) $(STAMP_DIR)
 
-$(BUILD_DIR)/buildroot-config/auto.conf: $(BUILDROOT_CONFIG)
+$(BUILD_DIR)/buildroot-config/auto.conf: $(BR2_CONFIG)
 	$(MAKE1) $(EXTRAMAKEARGS) HOSTCC="$(HOSTCC_NOCCACHE)" HOSTCXX="$(HOSTCXX_NOCCACHE)" silentoldconfig
 
 prepare: $(BUILD_DIR)/buildroot-config/auto.conf
@@ -626,7 +626,7 @@
 	@$(call legal-manifest,buildroot,$(BR2_VERSION_FULL),GPLv2+,COPYING,not saved,HOST)
 	@$(call legal-warning,the Buildroot source code has not been saved)
 	@$(call legal-warning,the toolchain has not been saved)
-	@cp $(BUILDROOT_CONFIG) $(LEGAL_INFO_DIR)/buildroot.config
+	@cp $(BR2_CONFIG) $(LEGAL_INFO_DIR)/buildroot.config
 
 legal-info: dirs legal-info-clean legal-info-prepare $(TARGETS_LEGAL_INFO) \
 		$(REDIST_SOURCES_DIR_TARGET) $(REDIST_SOURCES_DIR_HOST)
@@ -683,7 +683,7 @@
 	KCONFIG_AUTOCONFIG=$(BUILD_DIR)/buildroot-config/auto.conf \
 	KCONFIG_AUTOHEADER=$(BUILD_DIR)/buildroot-config/autoconf.h \
 	KCONFIG_TRISTATE=$(BUILD_DIR)/buildroot-config/tristate.config \
-	BUILDROOT_CONFIG=$(BUILDROOT_CONFIG) \
+	BR2_CONFIG=$(BR2_CONFIG) \
 	BR2_EXTERNAL=$(BR2_EXTERNAL)
 
 xconfig: $(BUILD_DIR)/buildroot-config/qconf outputmakefile
@@ -724,7 +724,7 @@
 
 randpackageconfig: $(BUILD_DIR)/buildroot-config/conf outputmakefile
 	@mkdir -p $(BUILD_DIR)/buildroot-config
-	@grep -v BR2_PACKAGE_ $(BUILDROOT_CONFIG) > $(CONFIG_DIR)/.config.nopkg
+	@grep -v BR2_PACKAGE_ $(BR2_CONFIG) > $(CONFIG_DIR)/.config.nopkg
 	@grep '^config BR2_PACKAGE_' Config.in.legacy | \
 		while read config pkg; do \
 		echo "# $$pkg is not set" >> $(CONFIG_DIR)/.config.nopkg; done
@@ -735,7 +735,7 @@
 
 allyespackageconfig: $(BUILD_DIR)/buildroot-config/conf outputmakefile
 	@mkdir -p $(BUILD_DIR)/buildroot-config
-	@grep -v BR2_PACKAGE_ $(BUILDROOT_CONFIG) > $(CONFIG_DIR)/.config.nopkg
+	@grep -v BR2_PACKAGE_ $(BR2_CONFIG) > $(CONFIG_DIR)/.config.nopkg
 	@grep '^config BR2_PACKAGE_' Config.in.legacy | \
 		while read config pkg; do \
 		echo "# $$pkg is not set" >> $(CONFIG_DIR)/.config.nopkg; done
@@ -746,7 +746,7 @@
 
 allnopackageconfig: $(BUILD_DIR)/buildroot-config/conf outputmakefile
 	@mkdir -p $(BUILD_DIR)/buildroot-config
-	@grep -v BR2_PACKAGE_ $(BUILDROOT_CONFIG) > $(CONFIG_DIR)/.config.nopkg
+	@grep -v BR2_PACKAGE_ $(BR2_CONFIG) > $(CONFIG_DIR)/.config.nopkg
 	@$(COMMON_CONFIG_ENV) \
 		KCONFIG_ALLCONFIG=$(CONFIG_DIR)/.config.nopkg \
 		$< --allnoconfig $(CONFIG_CONFIG_IN)
@@ -818,7 +818,7 @@
 ifeq ($(O),output)
 	rm -rf $(O)
 endif
-	rm -rf $(BUILDROOT_CONFIG) $(CONFIG_DIR)/.config.old $(CONFIG_DIR)/.auto.deps
+	rm -rf $(BR2_CONFIG) $(CONFIG_DIR)/.config.old $(CONFIG_DIR)/.auto.deps
 
 help:
 	@echo 'Cleaning:'