Revert "get.sh: put tmpclone dirs in xbtmp"

This reverts commit 01a779d4eb.

This commit broke ./mk -d coreboot for vendor files in lbmk.

include/tree.sh

@@ -65,6 +65,8 @@ trees()
 	targets="$*"
 	cmd="build_targets $targets"
 	singletree "$project" && cmd="build_project"
+
+	remkdir "${tmpgit%/*}"
 }
 
 build_project()