kbuild: Small fixes

o When using "make -j<n>", the order in modversions.h could change,
  thus causing unnecessary rebuilds.
o Move a comment in Rules.make which I forgot when I moved the
  associated code.
o When descending into init/ during the final vmlinux link,
  add a '+' do tell make to use its normal "-j" jobserver handling.
o It'd be nice to get the logic between make clean and make mrproper
  clearer. I think make clean should remove all targets used in the
  actual build,
  make mrproper should remove the rest, build-specific files, like
  e.g. the .*.cmd files used to save dependencies and command lines
  and other temporary files.
  A real small step in the direction: Remove .tmpversion/.tmp-export-objs
  at mrproper time.

Makefile

@@ -225,7 +225,7 @@ define rule_link_vmlinux
 	echo Generating build number
 	. scripts/mkversion > .tmpversion
 	mv -f .tmpversion .version
-	$(MAKE) -C init
+	+$(MAKE) -C init
 	$(call cmd,cmd_link_vmlinux)
 	$(cmd_link_vmlinux)
 	echo 'cmd_$@ := $(cmd_link_vmlinux)' > $(@D)/.$(@F).cmd
@@ -353,7 +353,7 @@ include/linux/modversions.h: scripts/fixdep prepare FORCE
 	@( echo "#ifndef _LINUX_MODVERSIONS_H";\
 	   echo "#define _LINUX_MODVERSIONS_H"; \
 	   echo "#include <linux/modsetver.h>"; \
-	   for f in `cd .tmp_export-objs; find modules -name \*.ver -print`; do \
+	   for f in `cd .tmp_export-objs; find modules -name \*.ver -print | sort`; do \
 	     echo "#include <linux/$${f}>"; \
 	   done; \
 	   echo "#endif"; \
@@ -574,9 +574,8 @@ make_with_config: .config
 
 #	files removed with 'make clean'
 CLEAN_FILES += \
-	kernel/ksyms.lst include/linux/compile.h \
+	include/linux/compile.h \
 	vmlinux System.map \
-	.tmp* \
 	drivers/char/consolemap_deftbl.c drivers/video/promcon_tbl.c \
 	drivers/char/conmakehash \
 	drivers/char/drm/*-mod.c \
@@ -616,9 +615,11 @@ MRPROPER_FILES += \
 	.hdepend scripts/split-include scripts/docproc \
 	scripts/fixdep $(TOPDIR)/include/linux/modversions.h \
 	tags TAGS kernel.spec \
+	.tmpversion
 
 # 	directories removed with 'make mrproper'
 MRPROPER_DIRS += \
+	.tmp_export-objs \
 	include/config \
 	$(TOPDIR)/include/linux/modules
 
@@ -631,7 +632,7 @@ clean:	archclean
 	@find . \( -name \*.[oas] -o -name core -o -name .\*.cmd -o \
 		   -name .\*.tmp -o -name .\*.d \) -type f -print \
 		| grep -v lxdialog/ | xargs rm -f
-	@rm -rf $(CLEAN_FILES)
+	@rm -f $(CLEAN_FILES)
 	@$(MAKE) -C Documentation/DocBook clean
 
 mrproper: clean archmrproper

Rules.make

@@ -88,6 +88,9 @@ real-objs-m := $(foreach m, $(obj-m), $(if $($(m:.o=-objs)),$($(m:.o=-objs)),$(m
 # Get things started.
 # ==========================================================================
 
+# If a Makefile does define neither O_TARGET nor L_TARGET,
+# use a standard O_TARGET named "built-in.o"
+
 ifndef O_TARGET
 ifndef L_TARGET
 O_TARGET := built-in.o
@@ -173,9 +176,6 @@ cmd_as_o_S       = $(CC) -Wp,-MD,.$(subst /,_,$@).d $(a_flags) -c -o $@ $<
 %.o: %.S FORCE
 	$(call if_changed_dep,as_o_S)
 
-# If a Makefile does define neither O_TARGET nor L_TARGET,
-# use a standard O_TARGET named "built-in.o"
-
 # Build the compiled-in targets
 # ---------------------------------------------------------------------------