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 998be765cf.

ARMeilleure/Common/BitMap.cs

@@ -35,7 +35,7 @@ namespace ARMeilleure.Common
             }
         }
 
-        public void Reset(int initialCapacity)
+        public BitMap Reset(int initialCapacity)
         {
             int count = (initialCapacity + IntMask) / IntSize;
 
@@ -50,6 +50,8 @@ namespace ARMeilleure.Common
             {
                 _masks.Add(0);
             }
+
+            return this;
         }
 
         public bool Set(int bit)