mem_tracker: Provide ctor for embedded union (and name it so we can)
mem_tracker: Provide ctor for embedded union (and name it so we can)

VkSwapChainCreateInfoWSI has a nontrivial default constructor due to
having an embedded VkSwapChain handle.

From the C++11 standard, 9.5:

  "If any non-static data member of a union has a non-trivial default
  constructor (12.1), copy constructor (12.8), move constructor (12.8),
  copy assignment operator (12.8), move assignment operator (12.8), or
  destructor (12.4), the corresponding member function of the union must
  be user-provided or it will be implicitly deleted (8.4.3) for the
  union."

Signed-off-by: Chris Forbes <5dcac483e7a6e31a5cbe89f38cc69dff8ee93dac@ijw.co.nz>

KhronosGroup/Vulkan-Tools,KhronosGroup/Vulkan-Tools,KhronosGroup/Vulkan-Tools,KhronosGroup/Vulkan-Tools