lib.sh: move singletree() to git.sh

it is primarily used there, and then in mk,
but only after git.sh is sourced.

Signed-off-by: Leah Rowe <leah@libreboot.org>

include/git.sh

@@ -66,6 +66,15 @@ git_prep()
 	mv "$tmpgit" "$_loc" || $err "git_prep: !mv $tmpgit $_loc"
 }
 
+# return 0 if project is single-tree, otherwise 1
+# e.g. coreboot is multi-tree, so 1
+singletree()
+{
+	for targetfile in "config/${1}/"*/target.cfg; do
+		[ -e "$targetfile" ] && [ -f "$targetfile" ] && return 1; :
+	done; :
+}
+
 fetch_submodule()
 {
 	mcfgdir="$mdir/${1##*/}"; eval \