kbuild: use relative path more to include Makefile

Prior to this commit, it was impossible to use relative path to
include Makefiles from the top level Makefile because the option
"--include-dir=$(srctree)" becomes effective when Make enters into
sub Makefiles.

To use relative path in any places, this commit moves the option
above the "sub-make" target.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>
diff --git a/Makefile b/Makefile
index d3726e5..929d805 100644
--- a/Makefile
+++ b/Makefile
@@ -10,9 +10,10 @@
 # Comments in this file are targeted only to the developer, do not
 # expect to learn how to build the kernel reading this file.
 
-# Do not use make's built-in rules and variables
-# (this increases performance and avoids hard-to-debug behaviour);
-MAKEFLAGS += -rR
+# o Do not use make's built-in rules and variables
+#   (this increases performance and avoids hard-to-debug behaviour);
+# o Look for make include files relative to root of kernel src
+MAKEFLAGS += -rR --include-dir=$(CURDIR)
 
 # Avoid funny character set dependencies
 unexport LC_ALL
@@ -344,12 +345,9 @@
 export COMPILER
 endif
 
-# Look for make include files relative to root of kernel src
-MAKEFLAGS += --include-dir=$(srctree)
-
 # We need some generic definitions (do not try to remake the file).
-$(srctree)/scripts/Kbuild.include: ;
-include $(srctree)/scripts/Kbuild.include
+scripts/Kbuild.include: ;
+include scripts/Kbuild.include
 
 # Make variables (CC, etc...)
 AS		= $(CROSS_COMPILE)as
@@ -533,7 +531,7 @@
 # Read arch specific Makefile to set KBUILD_DEFCONFIG as needed.
 # KBUILD_DEFCONFIG may point out an alternative default configuration
 # used for 'make defconfig'
-include $(srctree)/arch/$(SRCARCH)/Makefile
+include arch/$(SRCARCH)/Makefile
 export KBUILD_DEFCONFIG KBUILD_KCONFIG
 
 config: scripts_basic outputmakefile FORCE
@@ -609,7 +607,7 @@
 # Defaults to vmlinux, but the arch makefile usually adds further targets
 all: vmlinux
 
-include $(srctree)/arch/$(SRCARCH)/Makefile
+include arch/$(SRCARCH)/Makefile
 
 KBUILD_CFLAGS	+= $(call cc-option,-fno-delete-null-pointer-checks,)
 
@@ -781,8 +779,8 @@
 	KBUILD_CFLAGS += -DCC_HAVE_ASM_GOTO
 endif
 
-include $(srctree)/scripts/Makefile.kasan
-include $(srctree)/scripts/Makefile.extrawarn
+include scripts/Makefile.kasan
+include scripts/Makefile.extrawarn
 
 # Add user supplied CPPFLAGS, AFLAGS and CFLAGS as the last assignments
 KBUILD_CPPFLAGS += $(KCPPFLAGS)