only update version header as needed

Constantly rebuilding the version header will force useless relinking, so we
simply need to compare the new header with the existing one before updating
it.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

diff --git a/Makefile b/Makefile
index 9225a2d..969ce42 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -343,7 +343,8 @@ $(VERSION_FILE):
                echo -n "$(U_BOOT_VERSION)" ; \
                echo -n $(shell $(CONFIG_SHELL) $(TOPDIR)/tools/setlocalversion \
                         $(TOPDIR)) ; \
-               echo "\"" ) > $(VERSION_FILE)
+               echo "\"" ) > $@.tmp
+               @cmp -s $@ $@.tmp && rm -f $@.tmp || mv -f $@.tmp $@
 
 gdbtools:
                $(MAKE) -C tools/gdb all || exit 1