x86/build: Supress "Nothing to be done for ..." messages

When we build an already built kernel again, arch/x86/syscalls/Makefile
and arch/x86/tools/Makefile emits "Nothing to be done for ..."
messages.

Here is the command log:

  $ make defconfig
     [ snip ]
  $ make
     [ snip ]
  $ make
  make[1]: Nothing to be done for `all'.            <-----
  make[1]: Nothing to be done for `relocs'.         <-----
    CHK     include/config/kernel.release
    CHK     include/generated/uapi/linux/version.h

Besides not emitting those, "all" and "relocs" should be added to PHONY as well.
Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Acked-by: Peter Foley <pefoley2@pefoley.com>
Acked-by: Michal Marek <mmarek@suse.cz>
Link: http://lkml.kernel.org/r/1397093742-11144-1-git-send-email-yamada.m@jp.panasonic.comSigned-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/syscalls/Makefile

@@ -54,5 +54,7 @@ syshdr-$(CONFIG_X86_64)		+= syscalls_64.h
 
 targets	+= $(uapisyshdr-y) $(syshdr-y)
 
+PHONY += all
 all: $(addprefix $(uapi)/,$(uapisyshdr-y))
 all: $(addprefix $(out)/,$(syshdr-y))
+	@:

arch/x86/tools/Makefile

@@ -40,4 +40,6 @@ $(obj)/insn_sanity.o: $(srctree)/arch/x86/lib/insn.c $(srctree)/arch/x86/lib/ina
 HOST_EXTRACFLAGS += -I$(srctree)/tools/include
 hostprogs-y	+= relocs
 relocs-objs     := relocs_32.o relocs_64.o relocs_common.o
+PHONY += relocs
 relocs: $(obj)/relocs
+	@: