kbuild: rename abs_objtree to abs_output

'objtree' refers to the top of the output directory of kernel builds.

Rename abs_objtree to a more generic name, to better reflect its use in
the context of external module builds.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>

Makefile

@@ -40,7 +40,7 @@ __all:
 
 this-makefile := $(lastword $(MAKEFILE_LIST))
 abs_srctree := $(realpath $(dir $(this-makefile)))
-abs_objtree := $(CURDIR)
+abs_output := $(CURDIR)
 
 ifneq ($(sub_make_done),1)
 
@@ -185,8 +185,8 @@ ifneq ($(KBUILD_OUTPUT),)
 # $(realpath ...) gets empty if the path does not exist. Run 'mkdir -p' first.
 $(shell mkdir -p "$(KBUILD_OUTPUT)")
 # $(realpath ...) resolves symlinks
-abs_objtree := $(realpath $(KBUILD_OUTPUT))
-$(if $(abs_objtree),,$(error failed to create output directory "$(KBUILD_OUTPUT)"))
+abs_output := $(realpath $(KBUILD_OUTPUT))
+$(if $(abs_output),,$(error failed to create output directory "$(KBUILD_OUTPUT)"))
 endif # ifneq ($(KBUILD_OUTPUT),)
 
 ifneq ($(words $(subst :, ,$(abs_srctree))), 1)
@@ -197,7 +197,7 @@ export sub_make_done := 1
 
 endif # sub_make_done
 
-ifeq ($(abs_objtree),$(CURDIR))
+ifeq ($(abs_output),$(CURDIR))
 # Suppress "Entering directory ..." if we are at the final work directory.
 no-print-directory := --no-print-directory
 else
@@ -221,7 +221,7 @@ $(filter-out $(this-makefile), $(MAKECMDGOALS)) __all: __sub-make
 
 # Invoke a second make in the output directory, passing relevant variables
 __sub-make:
-	$(Q)$(MAKE) $(no-print-directory) -C $(abs_objtree) \
+	$(Q)$(MAKE) $(no-print-directory) -C $(abs_output) \
 	-f $(abs_srctree)/Makefile $(MAKECMDGOALS)
 
 else # need-sub-make