kbuild: fix false positive -dirty tag caused by make-kpkg

make-kpkg modifies scripts/package/Makefile and deletes
scripts/package/builddeb as part of its build process.  Ignore these
changes so the tree isn't marked as -dirty, when it is just an
artifact of make-kpkg.  (make-kpkg clean restores the files to their
original state, and these helper scripts won't affect the final
compiled kernel in any way.)
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

scripts/setlocalversion

@@ -17,7 +17,8 @@ if head=`git rev-parse --verify HEAD 2>/dev/null`; then
 
 	# Are there uncommitted changes?
 	git update-index --refresh --unmerged > /dev/null
-	if git diff-index HEAD | read dummy; then
+	if git diff-index --name-only HEAD | grep -v "^scripts/package" \
+	    | read dummy; then
 		printf '%s' -dirty
 	fi