Refactor `NDS` and `DSi` to be objects (#1893)

* First crack at refactoring NDS and DSi into objects

- Remove all global/`static` variables in `NDS` and related classes
- Rely more on virtual dispatch when we need to pick methods at runtime
- Pass `NDS&` or `DSi&` to its constituent components where necessary
- Introduce some headers or move some definitions to break `#include` cycles

* Refactor the frontend to accommodate the core's changes

* Move up `SchedList`'s declaration

- Move it to before the components are initialized so the `map`s inside are initialized
- Fields in C++ are initialized in the order they're declared

* Fix a crash when allocating memory

* Fix JIT-free builds

* Fix GDB-free builds

* Fix Linux builds

- Explicitly qualify some member types in NDS, since they share the same name as their classes

* Remove an unnecessary template argument

- This was causing the build to fail on macOS

* Fix ARM and Android builds

* Rename `Constants.h` to `MemConstants.h`

* Add `NDS::IsRunning()`

* Use an `#include` guard instead of `#pragma once`

1 files changed, 4 insertions, 3 deletions

diff --git a/src/ARMJIT_x64/ARMJIT_Compiler.h b/src/ARMJIT_x64/ARMJIT_Compiler.h
index f38a6c3..fa6d78a 100644
--- a/src/ARMJIT_x64/ARMJIT_Compiler.h
+++ b/src/ARMJIT_x64/ARMJIT_Compiler.h
@@ -35,6 +35,7 @@ namespace melonDS
 {
 class ARMJIT;
 class ARMJIT_Memory;
+class NDS;
 const Gen::X64Reg RCPU = Gen::RBP;
 const Gen::X64Reg RCPSR = Gen::R15;
 
@@ -81,9 +82,9 @@ class Compiler : public Gen::XEmitter
 {
 public:
 #ifdef JIT_ENABLED
-    explicit Compiler(ARMJIT& jit);
+    explicit Compiler(melonDS::NDS& nds);
 #else
-    explicit Compiler(ARMJIT& jit) : XEmitter(), JIT(jit) {}
+    explicit Compiler(melonDS::NDS& nds) : XEmitter(), NDS(nds) {}
 #endif
 
     void Reset();
@@ -243,7 +244,7 @@ public:
     void CreateMethod(const char* namefmt, void* start, ...);
 #endif
 
-    ARMJIT& JIT;
+    melonDS::NDS& NDS;
     u8* FarCode {};
     u8* NearCode {};
     u32 FarSize {};