x86, um: now we can get rid of trivial uml headers

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
diff --git a/arch/um/Makefile b/arch/um/Makefile
index 4fc79f3..3474b10 100644
--- a/arch/um/Makefile
+++ b/arch/um/Makefile
@@ -66,6 +66,8 @@
 #This will adjust *FLAGS accordingly to the platform.
 include $(srctree)/$(ARCH_DIR)/Makefile-os-$(OS)
 
+KBUILD_CPPFLAGS += -I$(srctree)/arch/$(HEADER_ARCH)/include
+
 # -Derrno=kernel_errno - This turns all kernel references to errno into
 # kernel_errno to separate them from the libc errno.  This allows -fno-common
 # in KBUILD_CFLAGS.  Otherwise, it would cause ld to complain about the two different