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 9225a2d3503506d1c783f94c248dc0958977de18..969ce42ec06266767ef179ac00e051e937220a4c 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