loader: Fix bug in heap_free function to not do double free
loader: Fix bug in heap_free function to not do double free

KhronosGroup/Vulkan-LoaderAndValidationLayers,KhronosGroup/Vulkan-LoaderAndValidationLayers,Radamanthe/VulkanSamples,KhronosGroup/Vulkan-LoaderAndValidationLayers,elongbug/Vulkan-LoaderAndValidationLayers,elongbug/Vulkan-LoaderAndValidationLayers,critsec/Vulkan-LoaderAndValidationLayers,sashinde/VulkanTools,Radamanthe/VulkanSamples,KhronosGroup/Vulkan-LoaderAndValidationLayers,Radamanthe/VulkanSamples,Radamanthe/VulkanSamples,Radamanthe/VulkanSamples,sashinde/VulkanTools,critsec/Vulkan-LoaderAndValidationLayers,Radamanthe/VulkanSamples,sashinde/VulkanTools,elongbug/Vulkan-LoaderAndValidationLayers,sashinde/VulkanTools,critsec/Vulkan-LoaderAndValidationLayers,elongbug/Vulkan-LoaderAndValidationLayers,critsec/Vulkan-LoaderAndValidationLayers