Collapse AsSpan().Slice(..) calls into AsSpan(..) (#3145)

* Collapse AsSpan().Slice(..) calls into AsSpan(..)

Less code and a bit faster

* Collapse an Array.Clear(array, 0, array.Length) call to Array.Clear(array)

ARMeilleure/Translation/SsaConstruction.cs

@@ -113,7 +113,7 @@ namespace ARMeilleure.Translation
                     }
                 }
 
-                Array.Clear(localDefs, 0, localDefs.Length);
+                Array.Clear(localDefs);
             }
 
             // Second pass, rename variables with definitions on different blocks.