objtool: Fix cross-build

Stephen Rothwell reported this cross-compilation build failure:

| In file included from orc_dump.c:19:0:
| orc.h:21:10: fatal error: asm/orc_types.h: No such file or directory
| ...

Caused by:

  6a77cff ("objtool: Move synced files to their original relative locations")

Use the proper arch header files location, not the host-arch location.

Bisected-by: Stephen Rothwell <[email protected]>
Reported-by: Stephen Rothwell <[email protected]>
Signed-off-by: Josh Poimboeuf <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Linux-Next Mailing List <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/20171108030152.bd76eahiwjwjt3kp@treble
Signed-off-by: Ingo Molnar <[email protected]>

Author: jpoimboe

tools/objtool/Makefile

@@ -27,7 +27,7 @@ all: $(OBJTOOL)
 
 INCLUDES := -I$(srctree)/tools/include \
 	    -I$(srctree)/tools/arch/$(HOSTARCH)/include/uapi \
-	    -I$(srctree)/tools/objtool/arch/$(HOSTARCH)/include
+	    -I$(srctree)/tools/objtool/arch/$(ARCH)/include
 WARNINGS := $(EXTRA_WARNINGS) -Wno-switch-default -Wno-switch-enum -Wno-packed
 CFLAGS   += -Wall -Werror $(WARNINGS) -fomit-frame-pointer -O2 -g $(INCLUDES)
 LDFLAGS  += -lelf $(LIBSUBCMD)