um: use the right ifdef around exports in user_syms.c

... the same one that controls whether elf_aux.o is included into the
build, bringing the vsyscall_e... into it.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Richard Weinberger <richard@nod.at>

arch/um/os-Linux/Makefile

@@ -13,8 +13,6 @@ USER_OBJS := $(user-objs-y) aio.o elf_aux.o execvp.o file.o helper.o irq.o \
 	main.o mem.o process.o registers.o sigio.o signal.o start_up.o time.o \
 	tty.o umid.o util.o
 
-CFLAGS_user_syms.o += -DSUBARCH_$(SUBARCH)
-
 HAVE_AIO_ABI := $(shell [ -r /usr/include/linux/aio_abi.h ] && \
 	echo -DHAVE_AIO_ABI )
 CFLAGS_aio.o += $(HAVE_AIO_ABI)

arch/um/os-Linux/user_syms.c

@@ -45,7 +45,7 @@ EXPORT_SYMBOL(readdir64);
 extern void truncate64(void) __attribute__((weak));
 EXPORT_SYMBOL(truncate64);
 
-#ifdef SUBARCH_i386
+#ifdef CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA
 EXPORT_SYMBOL(vsyscall_ehdr);
 EXPORT_SYMBOL(vsyscall_end);
 #endif