um: switch to -idirafter, get saner kern_constants.h out of that

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Richard Weinberger <richard@nod.at>

arch/um/Makefile

@@ -47,7 +47,7 @@ KBUILD_AFLAGS += $(ARCH_INCLUDE)
 
 USER_CFLAGS = $(patsubst $(KERNEL_DEFINES),,$(patsubst -D__KERNEL__,,\
 	$(patsubst -I%,,$(KBUILD_CFLAGS)))) $(ARCH_INCLUDE) $(MODE_INCLUDE) \
-	$(filter -I%,$(CFLAGS)) -D_FILE_OFFSET_BITS=64
+	$(filter -I%,$(CFLAGS)) -D_FILE_OFFSET_BITS=64 -idirafter include
 
 include $(srctree)/$(ARCH_DIR)/Makefile-$(SUBARCH)
 
@@ -149,6 +149,6 @@ $(SHARED_HEADERS)/user_constants.h: $(ARCH_DIR)/sys-$(SUBARCH)/user-offsets.s
 
 $(SHARED_HEADERS)/kern_constants.h:
 	$(Q)mkdir -p $(dir $@)
-	$(Q)echo '#include "../../../../include/generated/asm-offsets.h"' >$@
+	$(Q)echo '#include <generated/asm-offsets.h>' >$@
 
 export SUBARCH USER_CFLAGS CFLAGS_NO_HARDENING OS HEADER_ARCH DEV_NULL_PATH