libsel4: fix licenses

- some were incorrectly marked GPL (libsel4 is BSD)
- update NICTA --> DATA61 etc
- fix tags D61 --> DATA61
- update year to 2017

SELFOUR-836: arm-hyp: Config option for saving/loading vs trapping debug state

Provides a configuration option for enabling HDCR.TD* traps, or saving and loading debug
state on VCPU switches. Currently verification only plans to support the trap setting.

As this option complicates all of the #ifdef's related to debug registers even further,
abstractions for enabling/disabling each individual piece of the debug code for different
configuration options are also implemented.

Part of these refactored #ifdef guards was to remove the guards completely from libsel4
around the definitions of the number of breakpoints and watchpoints.

SELFOUR-836: Disable debug context save/restore between VMs

This patch disables the debug register state save and restore on ARM-hyp,
such that Guest VMs can now interfere with one another and trigger
one another for certain limited scenarios. This will be undone later on.

ARM-HYP: Add support for save/restore of debug registers

As things are now, the Guest VMs can modify the debug registers at will
from non-secure PL1, and the kernel does nothing to ensure that guest VM
debug coprocessor registers are preserved.

This is a preliminary patch that simply hooks into vcpu_save and saves the
CPU's debug coprocessor registers when saving VCPU state.

For restoring the debug registers on switching to a VCPU, we just re-use
restore_user_debug_context, which is already called in restore_user_context.
(Restore_user_context is called by c_handle_vcpu_fault()). Specifically,
we modify the used_breakpoints_bf so that restore_user_debug_context()
will always pop all the debug context.

This patch only covers the breakpoint and watchpoint registers,
and it doesn't cover the entire debug coprocessor, which is another
conversation.

s/D61/DATA61/ in license headers for consistency

Replace #pragma once with include guards

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.