get rid of the last symlink in uml build

We need to make asm-offsets.h contents visible for objects built
with userland headers.  Instead of creating a symlink, just have the
file with equivalent include (relative to location of header) created
once.  That kills the last symlink used in arch/um builds.

Additionally, both generated headers can become dependencies of
archprepare now, killing the misuse of prepare.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/um/Makefile

@@ -22,10 +22,11 @@ MODE_INCLUDE	+= -I$(srctree)/$(ARCH_DIR)/include/shared/skas
 
 include $(srctree)/$(ARCH_DIR)/Makefile-skas
 
-ARCH_INCLUDE	:= -I$(srctree)/$(ARCH_DIR)/include/shared
+SHARED_HEADERS	:= $(ARCH_DIR)/include/shared
+ARCH_INCLUDE	:= -I$(srctree)/$(SHARED_HEADERS)
 ARCH_INCLUDE	+= -I$(srctree)/$(ARCH_DIR)/sys-$(SUBARCH)/shared
 ifneq ($(KBUILD_SRC),)
-ARCH_INCLUDE	+= -I$(ARCH_DIR)/include/shared # for two generated files
+ARCH_INCLUDE	+= -I$(SHARED_HEADERS)
 endif
 KBUILD_CPPFLAGS += -I$(srctree)/$(ARCH_DIR)/sys-$(SUBARCH)
 
@@ -85,8 +86,8 @@ endef
 
 KBUILD_KCONFIG := arch/um/Kconfig.$(HEADER_ARCH)
 
-archprepare: $(ARCH_DIR)/include/shared/user_constants.h
-prepare: $(ARCH_DIR)/include/shared/kern_constants.h
+archprepare: $(SHARED_HEADERS)/user_constants.h
+archprepare: $(SHARED_HEADERS)/kern_constants.h
 
 LINK-$(CONFIG_LD_SCRIPT_STATIC) += -static
 LINK-$(CONFIG_LD_SCRIPT_DYN) += -Wl,-rpath,/lib
@@ -119,17 +120,13 @@ endef
 # 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 \
-	$(ARCH_DIR)/include/shared/user_constants.h \
-	$(ARCH_DIR)/include/shared/kern_constants.h
+	$(SHARED_HEADERS)/user_constants.h \
+	$(SHARED_HEADERS)/kern_constants.h
 
 archclean:
 	@find . \( -name '*.bb' -o -name '*.bbg' -o -name '*.da' \
 		-o -name '*.gcov' \) -type f -print | xargs rm -f
 
-$(objtree)/$(ARCH_DIR)/include/shared:
-	@echo '  MKDIR $@'
-	$(Q)mkdir -p $@
-
 # Generated files
 
 $(ARCH_DIR)/sys-$(SUBARCH)/user-offsets.s: FORCE
@@ -148,11 +145,11 @@ define filechk_gen-asm-offsets
          echo ""; )
 endef
 
-$(ARCH_DIR)/include/shared/user_constants.h: $(ARCH_DIR)/sys-$(SUBARCH)/user-offsets.s
+$(SHARED_HEADERS)/user_constants.h: $(ARCH_DIR)/sys-$(SUBARCH)/user-offsets.s
 	$(call filechk,gen-asm-offsets)
 
-$(ARCH_DIR)/include/shared/kern_constants.h: $(objtree)/$(ARCH_DIR)/include/shared
-	@echo '  SYMLINK $@'
-	$(Q)ln -sf ../../../../include/asm/asm-offsets.h $@
+$(SHARED_HEADERS)/kern_constants.h:
+	$(Q)mkdir -p $(dir $@)
+	$(Q)echo '#include "../../../../include/asm/asm-offsets.h"' >$@
 
 export SUBARCH USER_CFLAGS CFLAGS_NO_HARDENING OS HEADER_ARCH DEV_NULL_PATH