[Patch] UML build: fix missing posix_types.h

[WANG Cong <xiyou.wangcong@gmail.com>]

When building UML with 'O=foo' specified, I got:

CC      kernel/bounds.s
  In file included from
/home/wangcong/Projects/linux-2.6/include/linux/types.h:11,
                 from
/home/wangcong/Projects/linux-2.6/include/linux/page-flags.h:8,
                 from
/home/wangcong/Projects/linux-2.6/kernel/bounds.c:9:
/home/wangcong/Projects/linux-2.6/include/linux/posix_types.h:47:29:
error: asm/posix_types.h: No such file or directory
In file included from
/home/wangcong/Projects/linux-2.6/include/linux/page-flags.h:8,
                 from
/home/wangcong/Projects/linux-2.6/kernel/bounds.c:9:
/home/wangcong/Projects/linux-2.6/include/linux/types.h:12:23: error:
asm/types.h: No such file or directory
In file included from
/home/wangcong/Projects/linux-2.6/include/linux/page-flags.h:8,

Below patch fixed it, note, it is only tested for x86 and um.

Signed-off-by: WANG Cong <wangcong@zeuux.org>
Cc: sam@ravnborg.org
Cc: jdike@addtoit.com

---
diff --git a/Makefile b/Makefile
index aa527a4..39130d1 100644
--- a/Makefile
+++ b/Makefile
@@ -930,7 +930,8 @@ ifneq ($(KBUILD_SRC),)
 		/bin/false; \
 	fi;
 	$(Q)if [ ! -d include2 ]; then mkdir -p include2; fi;
-	$(Q)if [ -e $(srctree)/include/asm-$(SRCARCH)/system.h ]; then  \
+	$(Q)if [ -e $(srctree)/include/asm-$(SRCARCH)/system.h -o \
+		 -e $(objtree)/include/asm-$(SRCARCH)/system.h ] ; then \
 	    ln -fsn $(srctree)/include/asm-$(SRCARCH) include2/asm;     \
 	    fi
 endif