fs: add option to define path to custom rootfs skeleton

Signed-off-by: Dmytro Milinevskyy <milinevskyy@gmail.com>
Acked-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>
diff --git a/Makefile b/Makefile
index 59151cc..744cae4 100644
--- a/Makefile
+++ b/Makefile
@@ -367,6 +367,10 @@
 	@mkdir -p $(STAGING_DIR)/usr/include
 	@mkdir -p $(STAGING_DIR)/usr/bin
 
+ifeq ($(BR2_ROOTFS_SKELETON_CUSTOM),y)
+TARGET_SKELETON=$(BR2_ROOTFS_SKELETON_CUSTOM_PATH)
+endif
+
 $(BUILD_DIR)/.root:
 	mkdir -p $(TARGET_DIR)
 	if ! [ -d "$(TARGET_DIR)/bin" ]; then \