Makefile: make directories by Makefile.build

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 805c3c3..e3354aa 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -24,6 +24,13 @@
 	$(lib-y:.o=.S) $(extra-y:.o=.c) $(extra-y:.o=.S))
 OBJS	:= $(addprefix $(obj),$(obj-y))
 
+# $(obj-dirs) is a list of directories that contain object files
+obj-dirs := $(dir $(OBJS))
+
+# Create directories for object files if directory does not exist
+# Needed when obj-y := dir/file.o syntax is used
+_dummy := $(foreach d,$(obj-dirs), $(shell [ -d $(d) ] || mkdir -p $(d)))
+
 LGOBJS := $(addprefix $(obj),$(sort $(lib-y)))
 
 all: $(LIB) $(addprefix $(obj),$(extra-y))