File headers: add missing copyright, add MIT to SPDX licenses

intern/libmv/bundle.sh

@@ -1,4 +1,5 @@
 #!/bin/sh
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 if [ "x$1" = "x--i-really-know-what-im-doing" ] ; then
   echo Proceeding as requested by command line ...

intern/libmv/mkfiles.sh

@@ -1,4 +1,5 @@
 #!/bin/sh
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 find ./libmv/ -type f | sed -r 's/^\.\///' | sort > files.txt
 find ./third_party/ -type f | \