Update U-Boot's build timestamp on every compile

Use the GNU 'date' command to auto-generate a new U-Boot
timestamp on every compile.

Signed-off-by: Peter Tyser <ptyser@xes-inc.com>
diff --git a/Makefile b/Makefile
index 4eff1b5..11fc3b7 100644
--- a/Makefile
+++ b/Makefile
@@ -30,6 +30,7 @@
 else
 U_BOOT_VERSION = $(VERSION).$(PATCHLEVEL)$(EXTRAVERSION)
 endif
+TIMESTAMP_FILE = $(obj)include/timestamp_autogenerated.h
 VERSION_FILE = $(obj)include/version_autogenerated.h
 
 HOSTARCH := $(shell uname -m | \
@@ -261,7 +262,7 @@
 LIBS += post/libpost.a
 
 LIBS := $(addprefix $(obj),$(LIBS))
-.PHONY : $(LIBS) $(VERSION_FILE)
+.PHONY : $(LIBS) $(TIMESTAMP_FILE) $(VERSION_FILE)
 
 LIBBOARD = board/$(BOARDDIR)/lib$(BOARD).a
 LIBBOARD := $(addprefix $(obj),$(LIBBOARD))
@@ -353,13 +354,13 @@
 $(LDSCRIPT):	depend $(obj)include/autoconf.mk
 		$(MAKE) -C $(dir $@) $(notdir $@)
 
-$(NAND_SPL):	$(VERSION_FILE)	$(obj)include/autoconf.mk
+$(NAND_SPL):	$(TIMESTAMP_FILE) $(VERSION_FILE) $(obj)include/autoconf.mk
 		$(MAKE) -C nand_spl/board/$(BOARDDIR) all
 
 $(U_BOOT_NAND):	$(NAND_SPL) $(obj)u-boot.bin $(obj)include/autoconf.mk
 		cat $(obj)nand_spl/u-boot-spl-16k.bin $(obj)u-boot.bin > $(obj)u-boot-nand.bin
 
-$(ONENAND_IPL):	$(VERSION_FILE)	$(obj)include/autoconf.mk
+$(ONENAND_IPL):	$(TIMESTAMP_FILE) $(VERSION_FILE) $(obj)include/autoconf.mk
 		$(MAKE) -C onenand_ipl/board/$(BOARDDIR) all
 
 $(U_BOOT_ONENAND):	$(ONENAND_IPL) $(obj)u-boot.bin $(obj)include/autoconf.mk
@@ -372,6 +373,10 @@
 		 ) > $@.tmp
 		@cmp -s $@ $@.tmp && rm -f $@.tmp || mv -f $@.tmp $@
 
+$(TIMESTAMP_FILE):
+		@date +'#define U_BOOT_DATE "%b %d %C%y"' > $@
+		@date +'#define U_BOOT_TIME "%T"' >> $@
+
 gdbtools:
 		$(MAKE) -C tools/gdb all || exit 1
 
@@ -381,7 +386,7 @@
 env:
 		$(MAKE) -C tools/env all MTD_VERSION=${MTD_VERSION} || exit 1
 
-depend dep:	$(VERSION_FILE)
+depend dep:	$(TIMESTAMP_FILE) $(VERSION_FILE)
 		for dir in $(SUBDIRS) ; do $(MAKE) -C $$dir _depend ; done
 
 TAG_SUBDIRS += include
@@ -462,7 +467,7 @@
 else	# !config.mk
 all $(obj)u-boot.hex $(obj)u-boot.srec $(obj)u-boot.bin \
 $(obj)u-boot.img $(obj)u-boot.dis $(obj)u-boot \
-$(SUBDIRS) $(VERSION_FILE) gdbtools updater env depend \
+$(SUBDIRS) $(TIMESTAMP_FILE) $(VERSION_FILE) gdbtools updater env depend \
 dep tags ctags etags cscope $(obj)System.map:
 	@echo "System not configured - see README" >&2
 	@ exit 1
@@ -3274,7 +3279,7 @@
 	@rm -f $(obj)include/bmp_logo.h
 	@rm -f $(obj)nand_spl/{u-boot-spl,u-boot-spl.map,System.map}
 	@rm -f $(obj)onenand_ipl/onenand-{ipl,ipl.bin,ipl-2k.bin,ipl-4k.bin,ipl.map}
-	@rm -f $(obj)api_examples/demo $(VERSION_FILE)
+	@rm -f $(obj)api_examples/demo $(TIMESTAMP_FILE) $(VERSION_FILE)
 	@find $(OBJTREE) -type f \
 		\( -name 'core' -o -name '*.bak' -o -name '*~' \
 		-o -name '*.o'	-o -name '*.a'	\) -print \