builddeb: Fix rootless build in setuid/setgid directory

Building 5.10-rc1 in a setgid directory failed with the following
error:

dpkg-deb: error: control directory has bad permissions 2755 (must be
>=0755 and <=0775)

When building with fakeroot, the earlier chown call would have removed
the setgid bits, but in a rootless build they remain.

Fixes: 3e85418 ("builddeb: Enable rootless builds")
Cc: Guillem Jover <guillem@hadrons.org>
Signed-off-by: Sven Joachim <svenjoac@gmx.de>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

Author: zwenna

scripts/package/builddeb

@@ -45,6 +45,8 @@ create_package() {
 	chmod -R go-w "$pdir"
 	# in case we are in a restrictive umask environment like 0077
 	chmod -R a+rX "$pdir"
+	# in case we build in a setuid/setgid directory
+	chmod -R ug-s "$pdir"
 
 	# Create the package
 	dpkg-gencontrol -p$pname -P"$pdir"