um: Use $(srctree) not $(KBUILD_SRC)

$(KBUILD_SRC) is not defined without O=, use $(srctree).

Reported-and-tested-by: Richard Weinberger <richard@nod.at>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

diff --git a/arch/um/Makefile b/arch/um/Makefile
index 9548ddc..28688e6 100644 (file)
--- a/arch/um/Makefile
+++ b/arch/um/Makefile
@@ -98,7 +98,7 @@ endef
 KBUILD_KCONFIG := $(HOST_DIR)/um/Kconfig
 
 archheaders:
-       $(Q)$(MAKE) -C '$(KBUILD_SRC)' KBUILD_SRC= \
+       $(Q)$(MAKE) -C '$(srctree)' KBUILD_SRC= \
                ARCH=$(SUBARCH) O='$(objtree)' archheaders
 
 archprepare: include/generated/user_constants.h