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.

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.

Fix trivial comment typos.

libsel4: fix licenses

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

SELFOUR-879: expose index and entry constants

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

This is to conform with existing style of checking configuration options

Explicitly pack bootinfo data structures

To prevent the kernel and root server having a different layout of these structs if they are
compiled with different flags etc they should be packed

libsel4: Optional public symbols for external interfaces

CONFIG_LIB_SEL4_PUBLIC_SYMBOLS=y will disable inlining for external
interfaces (except deprecated functions), thereby providing public
symbols for easy linkage with other languages.

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

libsel4: Make FORCE_LONG_ENUM actually force a long instead of an int

libsel4: Generate non inlined syscall invocations

For performing verification on libsel4 the syscall invocations need
to not be inlined. This provides a (somewhat hacky) way of doing that.

SELFOUR-365: libsel4: Use compile time offsets instead of hard coding offsets

libsel4: Make enum padding types one less in value so that they are INT_MAX

Having the padding types as INT_MAX + 1 means C++ compilers will end up using
a signed 64 bit integer, as that is the only type that can have a value that
large, as well as the negative values our enums typically contain

Release snapshot