Implement support for page sizes > 4KB (#4252)

* Implement support for page sizes > 4KB

* Check and work around more alignment issues

* Was not meant to change this

* Use MemoryBlock.GetPageSize() value for signal handler code

* Do not take the path for private allocations if host supports 4KB pages

* Add Flags attribute on MemoryMapFlags

* Fix dirty region size with 16kb pages

Would accidentally report a size that was too high (generally 16k instead of 4k, uploading 4x as much data)

Co-authored-by: riperiperi <rhy3756547@hotmail.com>

Ryujinx.Cpu/PrivateMemoryAllocation.cs

@@ -0,0 +1,41 @@
+using Ryujinx.Memory;
+using System;
+
+namespace Ryujinx.Cpu
+{
+    struct PrivateMemoryAllocation : IDisposable
+    {
+        private readonly PrivateMemoryAllocator _owner;
+        private readonly PrivateMemoryAllocator.Block _block;
+
+        public bool IsValid => _owner != null;
+        public MemoryBlock Memory => _block?.Memory;
+        public ulong Offset { get; }
+        public ulong Size { get; }
+
+        public PrivateMemoryAllocation(
+            PrivateMemoryAllocator owner,
+            PrivateMemoryAllocator.Block block,
+            ulong offset,
+            ulong size)
+        {
+            _owner = owner;
+            _block = block;
+            Offset = offset;
+            Size = size;
+        }
+
+        public (PrivateMemoryAllocation, PrivateMemoryAllocation) Split(ulong splitOffset)
+        {
+            PrivateMemoryAllocation left = new PrivateMemoryAllocation(_owner, _block, Offset, splitOffset);
+            PrivateMemoryAllocation right = new PrivateMemoryAllocation(_owner, _block, Offset + splitOffset, Size - splitOffset);
+
+            return (left, right);
+        }
+
+        public void Dispose()
+        {
+            _owner.Free(_block, Offset, Size);
+        }
+    }
+}