zink: remove compiled conditional for lavapipe usage

this is super annoying since it means that a build of zink cannot
be mix-and-matched with an existing build of lavapipe, e.g., for faster
bisecting

the env var should be sufficient to handle this, and if someone sets it
and doesn't have swrast enabled then they can deal with it

Acked-by: Dave Airlie <airlied@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/15844>

src/gallium/drivers/zink/meson.build

@@ -79,10 +79,6 @@ zink_nir_algebraic_c = custom_target(
 zink_c_args = []
 inc_zink_vk = []
 
-if with_swrast_vk
-  zink_c_args += '-DZINK_WITH_SWRAST_VK'
-endif
-
 # MoltenVK options
 if with_moltenvk_dir != ''
   inc_zink_vk  = [inc_zink_vk, include_directories( join_paths(with_moltenvk_dir, 'include') )]

src/gallium/drivers/zink/zink_screen.c

@@ -1283,7 +1283,6 @@ choose_pdev(struct zink_screen *screen)
    for (i = 0; i < pdev_count; ++i) {
       vkGetPhysicalDeviceProperties(pdevs[i], props);
 
-#ifdef ZINK_WITH_SWRAST_VK
       char *use_lavapipe = getenv("ZINK_USE_LAVAPIPE");
       if (use_lavapipe) {
          if (props->deviceType == VK_PHYSICAL_DEVICE_TYPE_CPU) {
@@ -1294,7 +1293,7 @@ choose_pdev(struct zink_screen *screen)
          }
          continue;
       }
-#endif
+
       if (props->deviceType != VK_PHYSICAL_DEVICE_TYPE_CPU) {
          screen->pdev = pdevs[i];
          screen->info.device_version = props->apiVersion;