Code improvements based on static analysis

See #488

include/vk_mem_alloc.h

diff --git a/include/vk_mem_alloc.h b/include/vk_mem_alloc.h
index b9c5d1c..3878a68 100644
--- a/include/vk_mem_alloc.h
+++ b/include/vk_mem_alloc.h
@@ -3982,7 +3982,7 @@
         // of the VK_KHR_maintenance5 extension.
         const VkBufferUsageFlags2CreateInfoKHR* const usageFlags2 =
             VmaPnextChainFind<VkBufferUsageFlags2CreateInfoKHR>(&createInfo, VK_STRUCTURE_TYPE_BUFFER_USAGE_FLAGS_2_CREATE_INFO_KHR);
-        if(usageFlags2 != 0)
+        if(usageFlags2 != VMA_NULL)
         {
             this->Value = usageFlags2->usage;
             return;
@@ -10153,7 +10153,6 @@
     explicit VmaVirtualBlock_T(const VmaVirtualBlockCreateInfo& createInfo);
     ~VmaVirtualBlock_T();
 
-    VkResult Init() { return VK_SUCCESS; }
     bool IsEmpty() const { return m_Metadata->IsEmpty(); }
     void Free(VmaVirtualAllocation allocation) { m_Metadata->Free((VmaAllocHandle)allocation); }
     void SetAllocationUserData(VmaVirtualAllocation allocation, void* userData) { m_Metadata->SetAllocationUserData((VmaAllocHandle)allocation, userData); }
@@ -11412,7 +11411,7 @@
 {
     const bool isUpperAddress = (createInfo.flags & VMA_ALLOCATION_CREATE_UPPER_ADDRESS_BIT) != 0;
 
-    VkDeviceSize freeMemory;
+    VkDeviceSize freeMemory = 0;
     {
         const uint32_t heapIndex = m_hAllocator->MemoryTypeIndexToHeapIndex(m_MemoryTypeIndex);
         VmaBudget heapBudget = {};
@@ -11993,6 +11992,8 @@
             m_AlgorithmState = vma_new_array(hAllocator, StateExtensive, m_BlockVectorCount);
         }
         break;
+    default:
+        ; // Do nothing.
     }
 }
 
@@ -12089,11 +12090,10 @@
         size_t currentCount = 0;
         VkDeviceSize freedBlockSize = 0;
 
-        uint32_t vectorIndex;
-        VmaBlockVector* vector;
+        uint32_t vectorIndex = 0;
+        VmaBlockVector* vector = VMA_NULL;
         if (m_PoolBlockVector != VMA_NULL)
         {
-            vectorIndex = 0;
             vector = m_PoolBlockVector;
         }
         else
@@ -12178,7 +12178,7 @@
             }
             freedBlockSize *= prevCount - currentCount;
 
-            VkDeviceSize dstBlockSize;
+            VkDeviceSize dstBlockSize = SIZE_MAX;
             {
                 VmaMutexLockRead lock(vector->GetMutex(), vector->GetAllocator()->m_UseMutex);
                 dstBlockSize = move.dstTmpAllocation->GetBlock()->m_pMetadata->GetSize();
@@ -12354,8 +12354,7 @@
     {
         if (++m_IgnoredAllocs < MAX_ALLOCS_TO_IGNORE)
             return CounterStatus::Ignore;
-        else
-            return CounterStatus::End;
+        return CounterStatus::End;
     }
 
     m_IgnoredAllocs = 0;
@@ -14574,11 +14573,9 @@
             bindBufferMemoryInfo.memoryOffset = memoryOffset;
             return (*m_VulkanFunctions.vkBindBufferMemory2KHR)(m_hDevice, 1, &bindBufferMemoryInfo);
         }
-        else
 #endif // #if VMA_VULKAN_VERSION >= 1001000 || VMA_BIND_MEMORY2
-        {
-            return VK_ERROR_EXTENSION_NOT_PRESENT;
-        }
+
+        return VK_ERROR_EXTENSION_NOT_PRESENT;
     }
     else
     {
@@ -15543,7 +15540,7 @@
 
     const VkDevice hDev = allocator->m_hDevice;
     const VmaVulkanFunctions* funcs = &allocator->GetVulkanFunctions();
-    VkResult res;
+    VkResult res = VK_SUCCESS;
 
 #if VMA_KHR_MAINTENANCE4 || VMA_VULKAN_VERSION >= 1003000
     if(funcs->vkGetDeviceBufferMemoryRequirements)
@@ -15595,7 +15592,7 @@
 
     const VkDevice hDev = allocator->m_hDevice;
     const VmaVulkanFunctions* funcs = &allocator->GetVulkanFunctions();
-    VkResult res;
+    VkResult res = VK_SUCCESS;
 
 #if VMA_KHR_MAINTENANCE4 || VMA_VULKAN_VERSION >= 1003000
     if(funcs->vkGetDeviceImageMemoryRequirements)
@@ -16712,6 +16709,11 @@
     VMA_DEBUG_LOG("vmaCreateVirtualBlock");
     VMA_DEBUG_GLOBAL_MUTEX_LOCK;
     *pVirtualBlock = vma_new(pCreateInfo->pAllocationCallbacks, VmaVirtualBlock_T)(*pCreateInfo);
+    return VK_SUCCESS;
+
+    /*
+    Code for the future if we ever need a separate Init() method that could fail:
+
     VkResult res = (*pVirtualBlock)->Init();
     if(res < 0)
     {
@@ -16719,6 +16721,7 @@
         *pVirtualBlock = VK_NULL_HANDLE;
     }
     return res;
+    */
 }
 
 VMA_CALL_PRE void VMA_CALL_POST vmaDestroyVirtualBlock(VmaVirtualBlock VMA_NULLABLE virtualBlock)