JIT optimizations and refactoring (#675)

* CPU/Recompiler: Use rel32 call where possible for no-args

* JitCodeBuffer: Support using preallocated buffer

* CPU/Recompiler/AArch64: Use bl instead of blr for short branches

* CPU/CodeCache: Allocate recompiler buffer in program space

This means we don't need 64-bit moves for every call out of the
recompiler.

* GTE: Don't store as u16 and load as u32

* CPU/Recompiler: Add methods to emit global load/stores

* GTE: Convert class to namespace

* CPU/Recompiler: Call GTE functions directly

* Settings: Turn into a global variable

* GPU: Replace local pointers with global

* InterruptController: Turn into a global pointer

* System: Replace local pointers with global

* Timers: Turn into a global instance

* DMA: Turn into a global instance

* SPU: Turn into a global instance

* CDROM: Turn into a global instance

* MDEC: Turn into a global instance

* Pad: Turn into a global instance

* SIO: Turn into a global instance

* CDROM: Move audio FIFO to the heap

* CPU/Recompiler: Drop ASMFunctions

No longer needed since we have code in the same 4GB window.

* CPUCodeCache: Turn class into namespace

* Bus: Local pointer -> global pointers

* CPU: Turn class into namespace

* Bus: Turn into namespace

* GTE: Store registers in CPU state struct

Allows relative addressing on ARM.

* CPU/Recompiler: Align code storage to page size

* CPU/Recompiler: Fix relative branches on A64

* HostInterface: Local references to global

* System: Turn into a namespace, move events out

* Add guard pages

* Android: Fix build

src/core/settings.cpp

@@ -4,6 +4,8 @@
 #include <algorithm>
 #include <array>
 
+Settings g_settings;
+
 const char* SettingInfo::StringDefaultValue() const
 {
   return default_value ? default_value : "";