Generalize tail continues (#1298)

* Generalize tail continues

* Fix DecodeBasicBlock

`Next` and `Branch` would be null, which is not the state expected by
the branch instructions. They end up branching or falling into a block
which is never populated by the `Translator`. This causes an assert to
be fired when building the CFG.

* Clean up Decode overloads

* Do not synchronize when branching into exit block

If we're branching into an exit block, that exit block will tail
continue into another translation which already has a synchronization.

* Remove A32 predicate tail continue

If `block` is not an exit block then the `block.Next` must exist (as
per the last instruction of `block`).

* Throw if decoded 0 blocks

Address gdkchan's feedback

* Rebuild block list instead of setting to null

Address gdkchan's feedback

ARMeilleure/Decoders/Block.cs

@@ -12,6 +12,7 @@ namespace ARMeilleure.Decoders
         public Block Branch { get; set; }
 
         public bool TailCall { get; set; }
+        public bool Exit     { get; set; }
 
         public List<OpCode> OpCodes { get; private set; }
 
@@ -29,7 +30,7 @@ namespace ARMeilleure.Decoders
         {
             int splitIndex = BinarySearch(OpCodes, rightBlock.Address);
 
-            if ((ulong)OpCodes[splitIndex].Address < rightBlock.Address)
+            if (OpCodes[splitIndex].Address < rightBlock.Address)
             {
                 splitIndex++;
             }