Fixes in VmaAllocator_T::ImportVulkanFunctions

Hopefully fix Android #56

src/vk_mem_alloc.h

diff --git a/src/vk_mem_alloc.h b/src/vk_mem_alloc.h
index 39ddb08..a9e5d6d 100644
--- a/src/vk_mem_alloc.h
+++ b/src/vk_mem_alloc.h
@@ -15216,27 +15216,42 @@
 #if VMA_DEDICATED_ALLOCATION

     if(m_UseKhrDedicatedAllocation)

     {

-        m_VulkanFunctions.vkGetBufferMemoryRequirements2KHR =

-            (PFN_vkGetBufferMemoryRequirements2KHR)vkGetDeviceProcAddr(m_hDevice, "vkGetBufferMemoryRequirements2KHR");

-        m_VulkanFunctions.vkGetImageMemoryRequirements2KHR =

-            (PFN_vkGetImageMemoryRequirements2KHR)vkGetDeviceProcAddr(m_hDevice, "vkGetImageMemoryRequirements2KHR");

+        if(m_VulkanFunctions.vkGetBufferMemoryRequirements2KHR == nullptr)

+        {

+            m_VulkanFunctions.vkGetBufferMemoryRequirements2KHR =

+                (PFN_vkGetBufferMemoryRequirements2KHR)vkGetDeviceProcAddr(m_hDevice, "vkGetBufferMemoryRequirements2KHR");

+        }

+        if(m_VulkanFunctions.vkGetImageMemoryRequirements2KHR == nullptr)

+        {

+            m_VulkanFunctions.vkGetImageMemoryRequirements2KHR =

+                (PFN_vkGetImageMemoryRequirements2KHR)vkGetDeviceProcAddr(m_hDevice, "vkGetImageMemoryRequirements2KHR");

+        }

     }

 #endif

 #if VMA_BIND_MEMORY2

     if(m_UseKhrBindMemory2)

     {

-        m_VulkanFunctions.vkBindBufferMemory2KHR =

-            (PFN_vkBindBufferMemory2KHR)vkGetDeviceProcAddr(m_hDevice, "vkBindBufferMemory2KHR");

-        m_VulkanFunctions.vkBindImageMemory2KHR =

-            (PFN_vkBindImageMemory2KHR)vkGetDeviceProcAddr(m_hDevice, "vkBindImageMemory2KHR");

+        if(m_VulkanFunctions.vkBindBufferMemory2KHR == nullptr)

+        {

+            m_VulkanFunctions.vkBindBufferMemory2KHR =

+                (PFN_vkBindBufferMemory2KHR)vkGetDeviceProcAddr(m_hDevice, "vkBindBufferMemory2KHR");

+        }

+        if(m_VulkanFunctions.vkBindImageMemory2KHR == nullptr)

+        {

+            m_VulkanFunctions.vkBindImageMemory2KHR =

+                (PFN_vkBindImageMemory2KHR)vkGetDeviceProcAddr(m_hDevice, "vkBindImageMemory2KHR");

+        }

     }

 #endif // #if VMA_BIND_MEMORY2

 #if VMA_MEMORY_BUDGET

     if(m_UseExtMemoryBudget && m_VulkanApiVersion < VK_MAKE_VERSION(1, 1, 0))

     {

         VMA_ASSERT(m_hInstance != VK_NULL_HANDLE);

-        m_VulkanFunctions.vkGetPhysicalDeviceMemoryProperties2KHR =

-            (PFN_vkGetPhysicalDeviceMemoryProperties2KHR)vkGetInstanceProcAddr(m_hInstance, "vkGetPhysicalDeviceMemoryProperties2KHR");

+        if(m_VulkanFunctions.vkGetPhysicalDeviceMemoryProperties2KHR == nullptr)

+        {

+            m_VulkanFunctions.vkGetPhysicalDeviceMemoryProperties2KHR =

+                (PFN_vkGetPhysicalDeviceMemoryProperties2KHR)vkGetInstanceProcAddr(m_hInstance, "vkGetPhysicalDeviceMemoryProperties2KHR");

+        }

     }

 #endif // #if VMA_MEMORY_BUDGET

 #endif // #if VMA_STATIC_VULKAN_FUNCTIONS == 1