[PATCH] kbuild: deb-pkg: Fix build error caused by lack of positionnal argument

[Marc Zyngier <maz@kernel.org>]

Since 8ef052389f7f ("kbuild: package: add -e and -u options to some
shell scripts"), building a debian package on my arm64 box fails:

$ make -j20 bindeb-pkg
  UPD     include/config/kernel.release
  GEN     debian
./scripts/package/mkdebian: 138: 1: parameter not set
make[2]: *** [scripts/Makefile.package:98: debian] Error 2
make[1]: *** [/home/maz/hot-poop/arm-platforms/Makefile:1538: bindeb-pkg] Error 2
make: *** [Makefile:224: __sub-make] Error 2

Applying the same pattern for substitution of undefined variables
seems to paper over the issue and brings the script back to life.

Fixes: 8ef052389f7f ("kbuild: package: add -e and -u options to some shell scripts")
Signed-off-by: Marc Zyngier <maz@kernel.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Nicolas Schier <nicolas@fjasle.eu>
---
 scripts/package/mkdebian | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/package/mkdebian b/scripts/package/mkdebian
index 196b14e8ad47..de8b460a46b4 100755
--- a/scripts/package/mkdebian
+++ b/scripts/package/mkdebian
@@ -135,7 +135,7 @@ else
 fi
 maintainer="${name} <${email}>"
 
-if [ "$1" = --need-source ]; then
+if [ "${1:+set}" = --need-source ]; then
 	gen_source
 fi
 
-- 
2.39.2