convert license headers to SPDX

Includes license review of 3rd-party files, adding missing upstream
headers, and moving the UNSW OZPLB license into its own file rather
than replicating it in the header.

Make style cleanups.

* misc/style-c.sh: Use the shell's && instead of "test -a", which is now
"obsolescent" per POSIX 2018 (see
http://pubs.opengroup.org/onlinepubs/9699919799.2018edition/).

* misc/style-all.sh: Indent branches of if-then-else conditional.

* misc/style-c.sh:
* misc/style-py.sh: [English] Prefer "in place" to "in-place" when not a
attributive modifier.

* misc/style-changed.sh:
* misc/style.sh: [English] Give comment sentences terminal punctuation.

* misc/cobbler:
* misc/style-c.sh:
* misc/style-cmake.sh:
* misc/style-py.sh:
* misc/style.sh: Standardize whitespace around CSIRO header.

common-tool: Moved some tools to misc

Moved some miscellaneous tools from common-tool to the misc
folder. Common-tool mainly consists of Kbuild items which
is no longer supported.