sh: thin archives fix linking

The VDSO symbols can't be linked into built-in.o when building with
thin archives, so change this to linking a new object file that is
included into the built-in.o.

Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Cc: linux-sh@vger.kernel.org
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

arch/sh/kernel/vsyscall/Makefile

-obj-y += vsyscall.o vsyscall-syscall.o
+obj-y += vsyscall.o vsyscall-syscall.o vsyscall-syms.o
 
 $(obj)/vsyscall-syscall.o: \
 	$(foreach F,trapa,$(obj)/vsyscall-$F.so)
 
 # Teach kbuild about targets
 targets += $(foreach F,trapa,vsyscall-$F.o vsyscall-$F.so)
-targets += vsyscall-note.o vsyscall.lds
+targets += vsyscall-note.o vsyscall.lds vsyscall-dummy.o
 
 # The DSO images are built using a special linker script
 quiet_cmd_syscall = SYSCALL $@
@@ -26,11 +26,11 @@ $(obj)/vsyscall-%.so: $(src)/vsyscall.lds $(obj)/vsyscall-%.o FORCE
 # We also create a special relocatable object that should mirror the symbol
 # table and layout of the linked DSO.  With ld -R we can then refer to
 # these symbols in the kernel code rather than hand-coded addresses.
-extra-y += vsyscall-syms.o
-$(obj)/built-in.o: $(obj)/vsyscall-syms.o
-$(obj)/built-in.o: ld_flags += -R $(obj)/vsyscall-syms.o
-
-SYSCFLAGS_vsyscall-syms.o = -r
-$(obj)/vsyscall-syms.o: $(src)/vsyscall.lds \
+SYSCFLAGS_vsyscall-dummy.o = -r
+$(obj)/vsyscall-dummy.o: $(src)/vsyscall.lds \
 			$(obj)/vsyscall-trapa.o $(obj)/vsyscall-note.o FORCE
 	$(call if_changed,syscall)
+
+LDFLAGS_vsyscall-syms.o := -r -R
+$(obj)/vsyscall-syms.o: $(obj)/vsyscall-dummy.o FORCE
+	$(call if_changed,ld)