common/uint128: Add missing header guard 

core/kernel: Migrate CodeSet to its own source files

common/CMakeLists: Amend boost dependency

When #2247 was created, thread_queue_list.h was the only user of
boost-related code, however #2252 moved the page table struct into
common, which makes use of Boost.ICL, so we need to add the dependency
to the common library's link interface again.

Fix crash caused by #2238.

common/thread_queue_list: Remove unnecessary dependency on boost

hwopus: Leverage multistream API for decoding regular Opus packets

Port citra-emu/citra#4684: "frontend: qt: fix a freeze where if you click on entry in the game list too fast, citra will hang"

The segment itself isn't actually modified.

Given this is utilized by the loaders, this allows avoiding inclusion of
the kernel process definitions where avoidable.

This also keeps the loading format for all executable data separate from
the kernel objects.

core/loader: Remove vestigial Linker class

Port citra-emu/citra#4697: "Fix getopt on systems where char is unsigned by default"

Given the class is now currently unused, it can be removed.

Neither the NRO or NSO loaders actually make use of the functions or
members provided by the Linker interface, so we can just remove the
inheritance altogether.

service/am: Supply remaining missing IAudioController functions

fsp_srv: Unstub SetCurrentProcess

input_common/sdl_impl: Minor cleanup in SDLState constructor

This just acts as a basic setter for a given PID value and performs no
further checking, so we can just store the passed in value.

All this does is supply a new volume level and a fade time in
nanoseconds for the volume transition to occur within.

Like the other volume setter, this mainly just sets a data member within
the service, nothing too special.

This function passes in the desired main applet and library applet
volume levels. We can then just pass those values back within the
relevant volume getter functions, allowing us to unstub those as well.

The initial values for the library and main applet volumes differ. The
main applet volume is 0.25 by default, while the library applet volume
is initialized to 1.0 by default in the services themselves.

kernel/thread: Amend conditional test and assignment within UpdatePriority()

CMakeLists: Raise minimum Boost requirement to 1.66.0

Required due to bugfix in boost for changed template resolving rules in GCC 7.3.0 in C++17 mode

core: Move PageTable struct into Common.

We don't need to universally capture by reference. We specifically just
need to capture the this pointer.

Specifying the time unit itself is sufficient here.

gl_rasterizer: Skip zero addr/sized regions on flush/invalidate.

ipc_helpers: Allow pushing and popping floating-point values

externals: Update opus to latest master

kernel/thread: Actually remove the definition of ExitCurrentThread()

video_core: Refactor to use MemoryManager interface for all memory access.

memory: Simplify rasterizer cache operations.