SELFOUR-806: aarch32 - Implement lazy FP save/restore

This commit implements lazy FP save/restore mechanism, required for user threads
when they use the FPU. The following caveats take place:

* Only support synchronous exceptions. No support for asynchronous ones.
* VFP opcodes are used instead of normal instructions to discard compiler warnings/errors.
* Support is limited to specific ARM subarchitectures we support and tested this commit on.
* Disable the FPU by default if users are not using it to avoid channels.
* FPU support is not verified yet.
* Will not work properly if using a VM that's running besides other VMs/threads that are using the FPU.

Fix licenses (the rest)

Check for configuration variables being 'defined' instead of 'true'

This is to conform with existing style of checking configuration options

smp: fix bugs when stalling remote core

- Restart TCB from inside the lock if it is waiting for anything other than IRQ
- Only replace the TCB with idle thread if it is in ThreadState_RunningVM state

Also, this makes the design generic to be shared with arm.

SELFOUR-745: ARM/SMP - Add lock/unlock code to kernel entry/exit points

aarch64: FPU lazy context switch

s/D61/DATA61/ in license headers for consistency

ARM/SMP: Prepare for ARM SMP adding stubs

Currently building ARM/SMP is broken. This commit:
1- Makes it possible to build ARM/SMP with stubs. Run-time SMP for ARM
DOES NOT WORK.
2- Can be a reference for future SMP targets to follow in order to
layout/add the minimal required files and functions needed to support SMP.
3- Builds for Sabre only. In order to support other platforms, ipi
interrupt ID should be defined in machine.h

ARM: Correct benchmark entry logging

trivial: correct usage of TRACK_KERNEL_ENTRIES

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.

Benchmark: Pack arch-independent benchmark-related files into separate directories

SELFOUR-615: arm entry point stubs

SELFOUR-615: create c_traps.c for arm outside mode

- move slowpath() and c_handle_syscall() to it
to mirror the x86 layout