minimal build fixes for uml (fallout from x86 merge)

 a) include/asm-um/arch can't just point to include/asm-$(SUBARCH) now
 b) arch/{i386,x86_64}/crypto are merged now
 c) subarch-obj needed changes
 d) cpufeature_64.h should pull "cpufeature_32.h", not <asm/cpufeature_32.h>
    since it can be included from asm-um/cpufeature.h
 e) in case of uml-i386 we need CONFIG_X86_32 for make and gcc, but not
    for Kconfig
 f) sysctl.c shouldn't do vdso_enabled for uml-i386 (actually, that one
    should be registered from corresponding arch/*/kernel/*, with ifdef
    going away; that's a separate patch, though).

With that and with Stephen's patch ("[PATCH net-2.6] uml: hard_header fix")
we have uml allmodconfig building both on i386 and amd64.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/um/Makefile b/arch/um/Makefile
index 989224f..0666729 100644
--- a/arch/um/Makefile
+++ b/arch/um/Makefile
@@ -176,9 +176,9 @@
 	@echo '  SYMLINK $@'
 ifneq ($(KBUILD_SRC),)
 	$(Q)mkdir -p $(objtree)/include/asm-um
-	$(Q)ln -fsn $(srctree)/include/asm-$(SUBARCH) include/asm-um/arch
+	$(Q)ln -fsn $(srctree)/include/asm-$(HEADER_ARCH) include/asm-um/arch
 else
-	$(Q)cd $(TOPDIR)/include/asm-um && ln -sf ../asm-$(SUBARCH) arch
+	$(Q)cd $(TOPDIR)/include/asm-um && ln -sf ../asm-$(HEADER_ARCH) arch
 endif
 
 $(objtree)/$(ARCH_DIR)/include:
@@ -232,4 +232,4 @@
 	@echo '  SYMLINK $@'
 	$(Q)ln -sf ../../../include/asm-um/asm-offsets.h $@
 
-export SUBARCH USER_CFLAGS CFLAGS_NO_HARDENING OS
+export SUBARCH USER_CFLAGS CFLAGS_NO_HARDENING OS HEADER_ARCH