add a script to generate the git snapshot.

scripts/generate-git-snapshot.sh

@@ -0,0 +1,19 @@
+#!/bin/sh
+#
+# Set LINUX_GIT to point to an upstream Linux git tree in your .bashrc or wherever.
+#
+# TODO: Generate the gitN number.
+#
+
+VER=$(grep patch sources | head -n1 | awk '{ print $2 }' | sed s/patch-// | sed s/.xz//)
+
+pushd $LINUX_GIT
+
+git diff v$VER.. > /tmp/patch-$VER-git
+xz -9 /tmp/patch-$VER-git
+DESC=$(git describe)
+popd
+
+mv /tmp/patch-$VER-git.xz .
+
+rpmdev-bumpspec -c "Linux $DESC" kernel.spec