Kbuild updates for v4.15 (2nd)

- Use pwd instead of /bin/pwd for portability
 
 - Clean up Makefiles
 
 - Fix ld-option for clang
 
 - Fix malloc'ed data size in Kconfig
 
 - Fix parallel building along with coccicheck
 
 - Fix a minor issue of package building
 
 - Prompt to use "rpm-pkg" instead of "rpm"
 
 - Clean up *.i and *.lst patterns by "make clean"
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Merge tag 'kbuild-v4.15-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull more Kbuild updates from Masahiro Yamada:

 - use 'pwd' instead of '/bin/pwd' for portability

 - clean up Makefiles

 - fix ld-option for clang

 - fix malloc'ed data size in Kconfig

 - fix parallel building along with coccicheck

 - fix a minor issue of package building

 - prompt to use "rpm-pkg" instead of "rpm"

 - clean up *.i and *.lst patterns by "make clean"

* tag 'kbuild-v4.15-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  kbuild: drop $(extra-y) from real-objs-y
  kbuild: clean up *.i and *.lst patterns by make clean
  kbuild: rpm: prompt to use "rpm-pkg" if "rpm" target is used
  kbuild: pkg: use --transform option to prefix paths in tar
  coccinelle: fix parallel build with CHECK=scripts/coccicheck
  kconfig/symbol.c: use correct pointer type argument for sizeof
  kbuild: Set KBUILD_CFLAGS before incl. arch Makefile
  kbuild: remove all dummy assignments to obj-
  kbuild: create built-in.o automatically if parent directory wants it
  kbuild: /bin/pwd -> pwd

scripts/Makefile.build

@@ -76,7 +76,7 @@ lib-target := $(obj)/lib.a
 obj-y += $(obj)/lib-ksyms.o
 endif
 
-ifneq ($(strip $(obj-y) $(obj-m) $(obj-) $(subdir-m) $(lib-target)),)
+ifneq ($(strip $(obj-y) $(need-builtin)),)
 builtin-target := $(obj)/built-in.o
 endif
 
@@ -566,7 +566,7 @@ targets := $(filter-out $(PHONY), $(targets))
 
 PHONY += $(subdir-ym)
 $(subdir-ym):
-	$(Q)$(MAKE) $(build)=$@
+	$(Q)$(MAKE) $(build)=$@ need-builtin=$(if $(findstring $@,$(subdir-obj-y)),1)
 
 # Add FORCE to the prequisites of a target to force it to be always rebuilt.
 # ---------------------------------------------------------------------------