kbuild: use git-archive for source package creation

Commit 5c3d1d0abb ("kbuild: add a tool to list files ignored by git")
added a new tool, scripts/list-gitignored. My intention was to create
source packages without cleaning the source tree, without relying on git.

Linus strongly objected to it, and suggested using 'git archive' instead.
[1] [2] [3]

This commit goes in that direction - Remove scripts/list-gitignored.c
and rewrites Makefiles and scripts to use 'git archive' for building
Debian and RPM source packages. It also makes 'make perf-tar*-src-pkg'
use 'git archive' again.

Going forward, building source packages is only possible in a git-managed
tree. Building binary packages does not require git.

[1]: https://lore.kernel.org/lkml/CAHk-=wi49sMaC7vY1yMagk7eqLK=1jHeHQ=yZ_k45P=xBccnmA@mail.gmail.com/
[2]: https://lore.kernel.org/lkml/CAHk-=wh5AixGsLeT0qH2oZHKq0FLUTbyTw4qY921L=PwYgoGVw@mail.gmail.com/
[3]: https://lore.kernel.org/lkml/CAHk-=wgM-W6Fu==EoAVCabxyX8eYBz9kNC88-tm9ExRQwA79UQ@mail.gmail.com/

Fixes: 5c3d1d0abb ("kbuild: add a tool to list files ignored by git")
Fixes: e0ca16749a ("kbuild: make perf-tar*-src-pkg work without relying on git")
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

scripts/check-git

@@ -0,0 +1,14 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# succeed if we are in a git repository
+
+srctree="$(dirname $0)/.."
+
+if ! git -C "${srctree}" rev-parse --verify HEAD >/dev/null 2>/dev/null; then
+	exit 1
+fi
+
+if ! test -z $(git -C "${srctree}" rev-parse --show-cdup 2>/dev/null); then
+	exit 1
+fi