layers: LX431, FENCE_NODE structures not initialized
layers: LX431, FENCE_NODE structures not initialized

The fenceMap structures are never initialized, resulting in indeterminate
behavior including bad draw_state validation messages from the smoke
test. Added a default constructor to FENCE_MAP.

Change-Id: I27e6b48e485bbb1e8774e2d5789e1e8d1b48020b

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