replacing all ifndef with pargma once

All the kernel header files now use pargma once rather than the ifndef,
as the pre-processed C files do not change while header files
are protected with pargma once. This will also solve any naming issues
caused by ifndef.

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: consistently attach return type

Add attach-return-type to astyle

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.

Move timestamp_t definition to types.h

it was causing circular references in files where it is defined and
hardware macros are also used.

Benchmark: share and use KS_LOG_PPTR and PPTR_TOP for x86 and ARM

SELFOUR-448 Benchmark: Track thread's CPU utilisation time

SELFOUR-446 Benchmark: Track syscall feature

Benchmark feature that currently:
- Keeps track of system calls info
- Start time
- Duration
- Capability type
- Invocation tag
- Log the number of invocations of each system call*
- Log the number of invocations for each capability type per syscall.
- Has 3 new syscalls (dump, reset, get size).
- This new feature uses the existing log buffer (which is 1MiB for x86
and ARM). Since the number of syscall invocations is not
deterministic, the logged number of invocations is limited by the size
of the buffer. I suggested to enable the users to pass their own
user-level buffer, to enable more flexibility, later.
- ENABLE_BENCHMARKS is now a parent config option of trace points and
system call track features, they can't be used at the same time.

Removed CONFIG_BENCHMARK config option. All checks for '#ifdef CONFIG_BENCHMARK' replaced with '#if CONFIG_MAX_NUM_TRACE_POINTS > 0'.

Added support for using multiple tracepoints at the same time.

x86: Make x86 the name of the architecture instead of IA32

IA32 is 32bit version of the x86 architecture. Whilst only IA32
is supported, much of the code is generic x86. Using a generic
x86 architecture will aid in future 64bit support