Convert license tags to SPDX identifiers

This commit also converts our own copyright headers to directly use
SPDX, but leaves all other copyright header intact, only adding the
SPDX ident. As far as possible this commit also merges multiple
Data61 copyright statements/headers into one for consistency.

style: set min-conditional-indent to 0

Given we use braces all the time conditional indents do not make code
cleaner.

style: consistently attach return type

Add attach-return-type to astyle

style: consistently align pointer with name

Run astyle with align-pointer=name

style: correct parenthesis padding

Use astyle's unpad-paren to unpad all parentheses that are not included
by pad-header, pad-oper, and pad-comma.

Upgrade to astyle 3.1

This produces minor changes

arm: Rename plat_cleanInvalidateCache

Rename plat_cleanInvalidateCache to plat_cleanInvalidateL2Cache to
indicate that it is a L2 cache maintenance operation only.

Use CONFIG_ variants of configuration definitions

The use of the CONFIG_ variants (that get declared in autoconf.h) for configuration
variables is preferred over definitions that get set somewhere in some Makefile

Remove many DONT_TRANSLATE markers.

The vast majority of the DONT_TRANSLATE markers in the kernel are used
to hide __asm__ statements and builtin functions
(e.g. __builtin_unreachable ()) from the C-to-Isabelle parser.

The parser now supports underscore identifiers and many __asm__ statements,
and the builtin functions are prototyped, meaning the vast majority of the
DONT_TRANSLATE markers can be dropped. The remaining markers cover functions
that must be treated specially.

[STYLE_FIX]

add seL4_BenchmarkFlushCaches() for arm and ia32

Available when CONFIG_ENABLE_BENCHMARKS is set, flushes caches for
running cold-cache benchmarks

[STYLE_FIX]

Disable L2 cache during initialisation

Fixes seL4/seL4#41.

SELFOUR-702: Correctly wait for clean to complete

SELFOUR-664: Support for prefetcher on Cortex-A9

Add support for enabling the L1 and L2 prefetcher on cortex-A9.

Mark some constant address pointers as const.

Pointers to structures at fixed hardware addresses such as gic_dist
and priv_timer can be known to be constant.

Added support for the Allwinner A20 platform (specifically the CubieTruck board)

Trivial: simplify #ifdef logic in L2C310 code

Add support for Zynq-7000

Release snapshot