um: Use HOST_DIR for mrproper

When HEADER_ARCH was introduced, the MRPROPER_FILES (then MRPROPER_DIRS) list wasn't adjusted, leaving SUBARCH as part of the path argument. This resulted in the "mrproper" target not cleaning up arch/x86/... when SUBARCH was specified. Since HOST_DIR is arch/$(HEADER_ARCH), use it instead to get the correct path.

---
 arch/um/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index 8186d4761bda..da4d5256af2f 100644
@@ -149,7 +149,7 @@ export CFLAGS_vmlinux := $(LINK-y) $(LINK_WRAPS) $(LD_FLAGS_CMDLINE) $(CC_FLAGS_
 # When cleaning we don't include .config, so we don't include
 # TT or skas makefiles and don't clean skas_ptregs.h.
 CLEAN_FILES += linux x.i gmon.out
-MRPROPER_FILES += arch/$(SUBARCH)/include/generated
+MRPROPER_FILES += $(HOST_DIR)/include/generated
 
 archclean:
 	@find . \( -name '*.bb' -o -name '*.bbg' -o -name '*.da' \

2.34.1

Build tested with/with-out patch, and I can see "mrproper" target correctly cleaning up now.

Applied to for-next/hardening, thanks!

[1/1] um: Use HOST_DIR for mrproper

      https://git.kernel.org/kees/c/48ad87a5be06

Kees Cook