Documentation: use subdir-y to avoid unnecessary built-in.o files

Change the Documentation makefiles from obj-m to subdir-y
to avoid generating unnecessary built-in.o files since nothing
in Documentation/ is ever linked in to vmlinux.

Signed-off-by: Peter Foley <[e-mail]>
Acked-by: Sam Ravnborg <[e-mail]>
Signed-off-by: Randy Dunlap <[e-mail]>
Signed-off-by: Jiri Kosina <[e-mail]>

Documentation/Makefile

···
-obj-m := DocBook/ accounting/ auxdisplay/ connector/ \
-	filesystems/ filesystems/configfs/ ia64/ laptops/ networking/ \
-	pcmcia/ spi/ timers/ watchdog/src/ misc-devices/mei/
+subdir-y := DocBook accounting auxdisplay connector \
+	filesystems filesystems ia64 laptops networking \
+	pcmcia spi timers watchdog misc-devices

Documentation/accounting/Makefile

···
-# kbuild trick to avoid linker error. Can be omitted if a module is built.
-obj- := dummy.o
-
 # List of programs to build
 hostprogs-y := getdelays
 

Documentation/auxdisplay/Makefile

···
-# kbuild trick to avoid linker error. Can be omitted if a module is built.
-obj- := dummy.o
-
 # List of programs to build
 hostprogs-y := cfag12864b-example
 

Documentation/filesystems/Makefile

···
-# kbuild trick to avoid linker error. Can be omitted if a module is built.
-obj- := dummy.o
-
 # List of programs to build
 hostprogs-y := dnotify_test
 

Documentation/ia64/Makefile

···
-# kbuild trick to avoid linker error. Can be omitted if a module is built.
-obj- := dummy.o
-
 # List of programs to build
 hostprogs-y := aliasing-test
 

Documentation/laptops/Makefile

···
-# kbuild trick to avoid linker error. Can be omitted if a module is built.
-obj- := dummy.o
-
 # List of programs to build
 hostprogs-y := dslm
 

Documentation/misc-devices/Makefile

···
+subdir-y := mei

Documentation/misc-devices/mei/Makefile

···
-# kbuild trick to avoid linker error. Can be omitted if a module is built.
-obj- := dummy.o
-
 # List of programs to build
 hostprogs-y := mei-amt-version
 HOSTCFLAGS_mei-amt-version.o += -I$(objtree)/usr/include

Documentation/networking/Makefile

···
-# kbuild trick to avoid linker error. Can be omitted if a module is built.
-obj- := dummy.o
-
-# Tell kbuild to always build the programs
-always := $(hostprogs-y)
-
-obj-m := timestamping/
+subdir-y := timestamping

Documentation/networking/timestamping/Makefile

···
-# kbuild trick to avoid linker error. Can be omitted if a module is built.
-obj- := dummy.o
-
 # List of programs to build
 hostprogs-y := timestamping hwtstamp_config
 

Documentation/pcmcia/Makefile

···
-# kbuild trick to avoid linker error. Can be omitted if a module is built.
-obj- := dummy.o
-
 # List of programs to build
 hostprogs-y := crc32hash
 

Documentation/spi/Makefile

···
-# kbuild trick to avoid linker error. Can be omitted if a module is built.
-obj- := dummy.o
-
 # List of programs to build
 hostprogs-y := spidev_test spidev_fdx
 

Documentation/timers/Makefile

···
-# kbuild trick to avoid linker error. Can be omitted if a module is built.
-obj- := dummy.o
-
 # List of programs to build
 hostprogs-$(CONFIG_X86) := hpet_example
 

Documentation/watchdog/Makefile

···
+subdir-y := src

Documentation/watchdog/src/Makefile

···
-# kbuild trick to avoid linker error. Can be omitted if a module is built.
-obj- := dummy.o
-
 # List of programs to build
 hostprogs-y := watchdog-simple watchdog-test