libmisc/shell/*: Relicense to 2-BSD

Many files in this directory were by persons and organizations
that have previously given relicensing permission. git history
was used to confirm authorship and contributions on files which
had unclear or missing copyrights.

Update #3053.

cpukit/libmisc/shell/shell-wait-for-input.c

@@ -1,3 +1,10 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+
+/**
+ * @file
+ * @brief Shell Wait for Input Implementation
+ */
+
 /*
  * Copyright (C) 2011 embedded brains GmbH & Co. KG
  *