PPTC & Pool Enhancements. (#1968)

* PPTC & Pool Enhancements.

* Avoid buffer allocations in CodeGenContext.GetCode(). Avoid stream allocations in PTC.PtcInfo.

Refactoring/nits.

* Use XXHash128, for Ptc.Load & Ptc.Save, x10 faster than Md5.

* Why not a nice Span.

* Added a simple PtcFormatter library for deserialization/serialization, which does not require reflection, in use at PtcJumpTable and PtcProfiler; improves maintainability and simplicity/readability of affected code.

* Nits.

* Revert #1987.

* Revert "Revert #1987."

This reverts commit 998be765cf7f7da5ff0c1c08de704c9012b0f49c.

Ryujinx.Memory/MemoryBlock.cs

@@ -40,8 +40,6 @@ namespace Ryujinx.Memory
             }
 
             Size = size;
-
-            GC.AddMemoryPressure((long)Size);
         }
 
         /// <summary>
@@ -283,8 +281,6 @@ namespace Ryujinx.Memory
             if (ptr != IntPtr.Zero)
             {
                 MemoryManagement.Free(ptr);
-
-                GC.RemoveMemoryPressure((long)Size);
             }
         }