Fix for out-of-bound accessing last free block in EXTENSIVE defragmentation algorithm.

Code by @medranSolus
See #232

Author: adam-sawicki-a

include/vk_mem_alloc.h

@@ -13289,7 +13289,7 @@ VkResult VmaDefragmentationContext_T::DefragmentPassEnd(VmaDefragmentationPassMo
                                 VMA_SWAP(vector->m_Blocks[i], vector->m_Blocks[vector->GetBlockCount() - ++m_ImmovableBlockCount]);
                                 if (state.firstFreeBlock != SIZE_MAX)
                                 {
-                                    if (i < state.firstFreeBlock - 1)
+                                    if (i + 1 < state.firstFreeBlock)
                                     {
                                         if (state.firstFreeBlock > 1)
                                             VMA_SWAP(vector->m_Blocks[i], vector->m_Blocks[--state.firstFreeBlock]);
@@ -13709,6 +13709,13 @@ bool VmaDefragmentationContext_T::ComputeDefragmentation_Extensive(VmaBlockVecto
     case StateExtensive::Operation::FindFreeBlockTexture:
     case StateExtensive::Operation::FindFreeBlockAll:
     {
+        // No more blocks to free, just perform fast realloc and move to cleanup
+        if (vectorState.firstFreeBlock == 0)
+        {
+            vectorState.operation = StateExtensive::Operation::Cleanup;
+            return ComputeDefragmentation_Fast(vector);
+        }
+
         // No free blocks, have to clear last one
         size_t last = (vectorState.firstFreeBlock == SIZE_MAX ? vector.GetBlockCount() : vectorState.firstFreeBlock) - 1;
         VmaBlockMetadata* freeMetadata = vector.GetBlock(last)->m_pMetadata;
@@ -13777,8 +13784,7 @@ bool VmaDefragmentationContext_T::ComputeDefragmentation_Extensive(VmaBlockVecto
             }
             vectorState.firstFreeBlock = last;
             // Nothing done, block found without reallocations, can perform another reallocs in same pass
-            if (prevMoveCount == m_Moves.size())
-                return ComputeDefragmentation_Extensive(vector, index);
+            return ComputeDefragmentation_Extensive(vector, index);
         }
         break;
     }