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.

mcs: scheduling context donation over ipc

After this commit, threads blocked on an endpoint can recieve a
scheduling context from the thread that wakes the blocked thread.

RFC-3: Update context for x86 to use FS and GS.

TLS_BASE virtual register is replaced with FS_BASE and GS_BASE virtual
registers.

The FS_BASE and GS_BASE virtual registers are moved to the end of the
context so they need not be considered in the kernel exit and entry
implementation.

Removed tracking of ES, DS, FS, and GS segment selectors on kernel entry
and exit.

ES and DS are clobbered on kernel entry with the RPL 3 selector for a
DPL 3 linear data segment.

FS is clobbered on exit with the RPL 3 selector for the DPL 3 segment
with FS_BASE as the base. This is done on exit to reload the value from
the GDT.

GS is clobbered on exit with the RPL 3 selector for the DPL 3 segment
with GS_BASE as the base. This is done on exit to reload the value from
the GDT.

Kernel entry and exit code is refactored, simplified, and improved in
light of the above changes.

x64: update verified config to use fsgsbase instr

The verification platform for x64 relies on the fsgsbase instruction.

Remove symlinked libsel4 files from include dir

These files can be included normally using libsel4 include paths. This
removes situations where the same file is available under different
include paths due to symlinking into different directory structures.

style: consistently align pointer with name

Run astyle with align-pointer=name

ia32: Set sensible defaults for FS and GS selectors

99.99% of the time this is what the user will want these set to in every thread, so
we might as well just set the sensible default here. Nothing stops the user overriding
this default later. This change will be unobservable to any existing (non broken) system

Move arch independent functions to generic files and HAVE_FPU config

x86: Extract common parts of `sanitiseRegister`

Creates a `Mode_sanitiseRegister` and factors out the common parts
of the 32 and 64 `sanitiseRegister` into a general x86 one

x86: Explicitly define VCPU general purpose registers

Previously the GP registers for a VCPU were defined in the 32-bit
arch registerset. This does not actually make sense as the mode
for the VCPU should be decoupled (and well defined) regardless of
the execution mode of the kernel. This commit provides an explicit
definition and register order for VCPU GP registers.

SELFOUR-413: changes for verification

Avoid using ptrs to arrays at all

Another macrofull change brought to your by verification. This should
avoid nasty proofs about const pointers.

SELFOUR-413: refactor libsel4 fault API

This is a *breaking API change*

This commit:

* makes seL4_Fault_tag_t common between the kernel and libsel4
* deprecates the existing functions from sel4/messages.h includes
* introduces a new fault API in sel4/faults.h and
* sel4/sel4_arch/faults.h
* deprecates seL4_GetTag(), as the function did not work without
the user calling seL4_SetTag() first (seL4_MessageInfo is passed
in registers and not set in the IPC buffer)
* removes previously deprecated functions (deprecated prior to 3.0.0)
* updates the seL4 manual to reflect the changes

Split fault types into arch/generic

Prior to this commit faults were separate
per architecture. This commit extracts the common
fault types and introduces arch specific faults,
reducing code duplication across architectures.

SELFOUR-287: 32-bit vt-x implementation

This is an implementation of vt-x for x86 kernels running in
ia32 mode.

ia32: Always forbid setting Trap Flag

If the user is allowed to set the Trap Flag then it can cause a kernel
exception by setting a thread to have TF enabled and running at a
'sysenter' instruction, which will result in a debug exception being
generated after the sysenter instruction has executed and in priviledged
mode.

x86: Define FLAGS bits instead of having magic numbers

x86: Rename [ER]FLAGS to FLAGS

Having a different name for the FLAGS register creates an unnecessary difference
between ia32 and x86_64 code since regardless of the name/size the bits in the
register mean exactly the same thing

x64: Refactor Arch_initContext

Split Arch_initContext into mode and arch portions

SELFOUR-499: X86, ARM: Add userspace invocations for hardware debugging

This commit implements the body of SELFOUR-499. The API exposes the x86 DR0-7
and ARM coprocessor 14 features to userspace by virtualizing them as context-
switched registers in the TCB. Implemented as TCB invocations. This feature is
only built when CONFIG_HARDWARE_DEBUG_API is selected.

* Add low-level support routines for setting, unsetting, getting, enabling
and disabling breakpoints.
* Add support for single-stepping as well.
^ Single-stepping is not supported on ARMv6 since the hardware
doesn't have support.
^ ARM implements single-stepping as instruction breakpoints
configured to fault on every instruction -- this is achieved through
the "mismatch" mode, which is only supported from ARMv7 onwards.
* Also support explicit software break requests, a la "BKPT" and "INT $3".

* New invocations:
* seL4_TCB_SetBreakpoint().
* seL4_TCB_GetBreakpoint().
* seL4_TCB_UnsetBreakpoint().
* seL4_TCB_ConfigureSingleStepping().
* New constants:
^ Event types:
^ seL4_InstructionBreakpoint.
^ seL4_DataBreakpoint.
^ seL4_SoftwareBreakRequest.
^ Access types:
^ seL4_BreakOnRead.
^ seL4_BreakOnWrite.
^ seL4_BreakOnReadWrite.
^ Exports:
^ seL4_NumHWBreakpoints.
^ seL4_NumExclusiveBreakpoints.
^ seL4_NumExclusiveWatchpoints.
^ seL4_NumDualFunctionMonitors.
^ seL4_FirstBreakpoint.
^ seL4_FirstWatchpoint.
^ seL4_FirstDualFunctionMonitor.

See documentation in the seL4 API manual.

x86: Rename FaultEIP and NextEIP to FaultIP and NextIP to allow for 32/64-bit independent code

x86: Move 32-bit specific files into 'mode' directories, and only build if IA32