nvk: add vulkan skeleton

This is enough to run vulkaninfo without crashing.

Jason:
* Drop a redundant nvk_device_entrypoints
* Add some VKAPI_ATTR and VKAPI_CALL
* nvk: Move EnumerateInstanceExtensionProperties to the top
  This way things are more-or-less in initialization order.  First the
  version then extensions then create the instance.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24326>

meson.build

@@ -242,6 +242,7 @@ with_broadcom_vk = _vulkan_drivers.contains('broadcom')
 with_imagination_vk = _vulkan_drivers.contains('imagination-experimental')
 with_imagination_srv = get_option('imagination-srv')
 with_microsoft_vk = _vulkan_drivers.contains('microsoft-experimental')
+with_nouveau_vk = _vulkan_drivers.contains('nouveau-experimental')
 with_any_vk = _vulkan_drivers.length() != 0
 
 with_any_broadcom = [
@@ -258,6 +259,7 @@ with_any_intel = [
   with_intel_tools,
   with_intel_vk,
 ].contains(true)
+with_any_nouveau = with_gallium_nouveau or with_nouveau_vk
 
 if with_swrast_vk and not with_gallium_softpipe
   error('swrast vulkan requires gallium swrast')
@@ -1575,7 +1577,7 @@ _libdrm_checks = [
   ['intel', with_gallium_i915],
   ['amdgpu', (with_amd_vk and not with_platform_windows) or with_gallium_radeonsi],
   ['radeon', (with_gallium_radeonsi or with_gallium_r300 or with_gallium_r600)],
-  ['nouveau', with_gallium_nouveau],
+  ['nouveau', with_any_nouveau],
 ]
 
 # Loop over the enables versions and get the highest libdrm requirement for all