layers: Add extension-enabled check to vkDestroySurfaceKHR().

layers: Add extension-enabled check to vkDestroySurfaceKHR().

Because the WSI functions are statically exported (i.e. no need to call gpa()
functions), the swapchain layer is supposed to issue an error if any WSI
function is called without its corresponding extension being enabled.  For
example, the VK_KHR_swapchain extension must be enabled before the
vkCreateSwapchainKHR() function is called.