kbuild: move modpost out of 'scripts' target

I am eagar to build under the scripts/ directory only with $(HOSTCC),
but scripts/mod/ highly depends on the $(CC) and target arch headers.
That it why the 'scripts' target must depend on 'asm-generic',
'gcc-plugins', and $(autoksyms_h).

Move it to the 'prepare0' stage. I know this is a cheesy workaround,
but better than the current situation.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

Makefile

@@ -1075,7 +1075,7 @@ include/config/kernel.release: $(srctree)/Makefile FORCE
 # Carefully list dependencies so we do not try to build scripts twice
 # in parallel
 PHONY += scripts
-scripts: scripts_basic scripts_dtc asm-generic gcc-plugins $(autoksyms_h)
+scripts: scripts_basic scripts_dtc
 	$(Q)$(MAKE) $(build)=$(@)
 
 # Things we need to do before we recursively start building the kernel
@@ -1113,6 +1113,7 @@ macroprepare: prepare1 archmacros
 archprepare: archheaders archscripts macroprepare scripts_basic gcc-plugins
 
 prepare0: archprepare
+	$(Q)$(MAKE) $(build)=scripts/mod
 	$(Q)$(MAKE) $(build)=.
 
 # All the preparing..

scripts/Makefile

@@ -37,9 +37,8 @@ build_unifdef: $(obj)/unifdef
 	@:
 
 subdir-$(CONFIG_MODVERSIONS) += genksyms
-subdir-y                     += mod
 subdir-$(CONFIG_SECURITY_SELINUX) += selinux
 subdir-$(CONFIG_GDB_SCRIPTS) += gdb
 
 # Let clean descend into subdirs
-subdir-	+= basic dtc kconfig package gcc-plugins
+subdir-	+= basic dtc kconfig mod package gcc-plugins

scripts/mod/Makefile

@@ -4,8 +4,6 @@ OBJECT_FILES_NON_STANDARD := y
 hostprogs-y	:= modpost mk_elfconfig
 always		:= $(hostprogs-y) empty.o
 
-CFLAGS_REMOVE_empty.o := $(ASM_MACRO_FLAGS)
-
 modpost-objs	:= modpost.o file2alias.o sumversion.o
 
 devicetable-offsets-file := devicetable-offsets.h