kbuild: simplify build, clean, modbuiltin shorthands

$(if $(KBUILD_SRC),$(srctree)/) was a useful strategy
to omit a long absolute path for in-source-tree build
prior to commit 890676c6
(kbuild: Use relative path when building in the source tree).

Now $(srctree) is "." when building in the source tree.
It would not be annoying to add "$(srctree)/" all the time.
Signed-off-by: NMasahiro Yamada <yamada.m@jp.panasonic.com>
Signed-off-by: NMichal Marek <mmarek@suse.cz>

Makefile

@@ -1568,7 +1568,7 @@ endif
 # Shorthand for $(Q)$(MAKE) -f scripts/Makefile.clean obj=dir
 # Usage:
 # $(Q)$(MAKE) $(clean)=dir
-clean := -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.clean obj
+clean := -f $(srctree)/scripts/Makefile.clean obj
 
 endif	# skip-makefile
 

scripts/Kbuild.include

@@ -171,13 +171,13 @@ ld-ifversion = $(shell [ $(call ld-version) $(1) $(2) ] && echo $(3))
 # Shorthand for $(Q)$(MAKE) -f scripts/Makefile.build obj=
 # Usage:
 # $(Q)$(MAKE) $(build)=dir
-build := -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.build obj
+build := -f $(srctree)/scripts/Makefile.build obj
 
 ###
 # Shorthand for $(Q)$(MAKE) -f scripts/Makefile.modbuiltin obj=
 # Usage:
 # $(Q)$(MAKE) $(modbuiltin)=dir
-modbuiltin := -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.modbuiltin obj
+modbuiltin := -f $(srctree)/scripts/Makefile.modbuiltin obj
 
 # Prefix -I with $(srctree) if it is not an absolute path.
 # skip if -I has no parameter

scripts/Makefile.clean

@@ -10,7 +10,7 @@ __clean:
 # Shorthand for $(Q)$(MAKE) scripts/Makefile.clean obj=dir
 # Usage:
 # $(Q)$(MAKE) $(clean)=dir
-clean := -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.clean obj
+clean := -f $(srctree)/scripts/Makefile.clean obj
 
 # The filename Kbuild has precedence over Makefile
 kbuild-dir := $(if $(filter /%,$(src)),$(src),$(srctree)/$(src))