busybox: add option to specify config fragments

Signed-off-by: Floris Bos <bos@je-eigen-domein.nl>
Acked-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/busybox/Config.in

@@ -20,6 +20,12 @@ config BR2_PACKAGE_BUSYBOX_CONFIG
 
 	  Most people will just use the default BusyBox configuration file.
 
+config BR2_PACKAGE_BUSYBOX_CONFIG_FRAGMENT_FILES
+	string "Additional BusyBox configuration fragment files"
+	help
+	  A space-separated list of configuration fragment files,
+	  that will be merged to the main BusyBox configuration file.
+
 config BR2_PACKAGE_BUSYBOX_SHOW_OTHERS
 	bool "Show packages that are also provided by busybox"
 	help

package/busybox/busybox.mk

@@ -46,6 +46,7 @@ ifndef BUSYBOX_CONFIG_FILE
 endif
 
 BUSYBOX_KCONFIG_FILE = $(BUSYBOX_CONFIG_FILE)
+BUSYBOX_KCONFIG_FRAGMENT_FILES = $(call qstrip,$(BR2_PACKAGE_BUSYBOX_CONFIG_FRAGMENT_FILES))
 BUSYBOX_KCONFIG_EDITORS = menuconfig xconfig gconfig
 BUSYBOX_KCONFIG_OPTS = $(BUSYBOX_MAKE_OPTS)