Fix bug in VmaAllocator_T::AllocateVulkanMemory for case when HeapSizeLimit is used

Closes #89 - thanks @JustSid !

src/vk_mem_alloc.h

diff --git a/src/vk_mem_alloc.h b/src/vk_mem_alloc.h
index c06144d..8678a22 100644
--- a/src/vk_mem_alloc.h
+++ b/src/vk_mem_alloc.h
@@ -15857,7 +15857,7 @@
             {

                 return VK_ERROR_OUT_OF_DEVICE_MEMORY;

             }

-            if(m_Budget.m_BlockBytes->compare_exchange_strong(blockBytes, blockBytesAfterAllocation))

+            if(m_Budget.m_BlockBytes[heapIndex].compare_exchange_strong(blockBytes, blockBytesAfterAllocation))

             {

                 break;

             }