Add support for a saving build objects in a separate directory.
Modifications are based on the linux kernel approach and
support two use cases:

  1) Add O= to the make command line
  'make O=/tmp/build all'

  2) Set environement variable BUILD_DIR to point to the desired location
  'export BUILD_DIR=/tmp/build'
  'make'

The second approach can also be used with a MAKEALL script
'export BUILD_DIR=/tmp/build'
'./MAKEALL'

Command line 'O=' setting overrides BUILD_DIR environent variable.

When none of the above methods is used the local build is performed and
the object files are placed in the source directory.
diff --git a/board/ep7312/Makefile b/board/ep7312/Makefile
index c53a3c7..c8c834f 100644
--- a/board/ep7312/Makefile
+++ b/board/ep7312/Makefile
@@ -1,4 +1,7 @@
 #
+# (C) Copyright 2006
+# Wolfgang Denk, DENX Software Engineering, wd@denx.de.
+#
 # (C) Copyright 2002
 # Sysgo Real-Time Solutions, GmbH <www.elinos.com>
 # Marius Groeger <mgroeger@sysgo.de>
@@ -24,12 +27,16 @@
 
 include $(TOPDIR)/config.mk
 
-LIB	= lib$(BOARD).a
+LIB	= $(obj)lib$(BOARD).a
 
-OBJS	:= ep7312.o flash.o
+COBJS	:= ep7312.o flash.o
 SOBJS	:= lowlevel_init.o
 
-$(LIB):	$(OBJS) $(SOBJS)
+SRCS	:= $(SOBJS:.o=.S) $(COBJS:.o=.c)
+OBJS	:= $(addprefix $(obj),$(COBJS))
+SOBJS	:= $(addprefix $(obj),$(SOBJS))
+
+$(LIB):	$(obj).depend $(OBJS) $(SOBJS)
 	$(AR) crv $@ $(OBJS) $(SOBJS)
 
 clean:
@@ -40,9 +47,9 @@
 
 #########################################################################
 
-.depend:	Makefile $(SOBJS:.o=.S) $(OBJS:.o=.c)
-		$(CC) -M $(CPPFLAGS) $(SOBJS:.o=.S) $(OBJS:.o=.c) > $@
+# defines $(obj).depend target
+include $(SRCTREE)/rules.mk
 
--include .depend
+sinclude $(obj).depend
 
 #########################################################################