gdkvulkancontext.c: Use pointers to hash VkShaderModule

VkShaderModule's may or may not be pointers depending on the target
platform, so use pointers to hash those handles to be safe, and retrieve
them from hashes accordingly.

Fixes build on 32-bit Windows at least.

gdk/gdkvulkancontext.c

@@ -1820,8 +1820,9 @@ gdk_display_unref_vulkan (GdkDisplay *display)
     {
       g_free (key);
       vkDestroyShaderModule (display->vk_device,
-                             value,
+                             *((VkShaderModule *)value),
                              NULL);
+      g_free (value);
     }
   g_hash_table_unref (display->vk_shader_modules);
 
@@ -1949,13 +1950,13 @@ VkShaderModule
 gdk_display_get_vk_shader_module (GdkDisplay *self,
                                   const char *resource_name)
 {
-  VkShaderModule shader;
+  VkShaderModule *shader;
   GError *error = NULL;
   GBytes *bytes;
 
   shader = g_hash_table_lookup (self->vk_shader_modules, resource_name);
   if (shader)
-    return shader;
+    return *shader;
 
   bytes = g_resources_lookup_data (resource_name, 0, &error);
   if (bytes == NULL)
@@ -1965,6 +1966,7 @@ gdk_display_get_vk_shader_module (GdkDisplay *self,
       return VK_NULL_HANDLE;
     }
 
+  shader = g_new0 (VkShaderModule, 1);
   if (GDK_VK_CHECK (vkCreateShaderModule, self->vk_device,
                                           &(VkShaderModuleCreateInfo) {
                                               .sType = VK_STRUCTURE_TYPE_SHADER_MODULE_CREATE_INFO,
@@ -1972,18 +1974,20 @@ gdk_display_get_vk_shader_module (GdkDisplay *self,
                                               .pCode = (uint32_t *) g_bytes_get_data (bytes, NULL),
                                           },
                                           NULL,
-                                          &shader) == VK_SUCCESS)
+                                          shader) == VK_SUCCESS)
     {
       g_hash_table_insert (self->vk_shader_modules, g_strdup (resource_name), shader);
     }
   else
     {
-      shader = VK_NULL_HANDLE;
+      g_free (shader);
+
+      return VK_NULL_HANDLE;
     }
 
   g_bytes_unref (bytes);
 
-  return shader;
+  return *shader;
 }
 
 #else /* GDK_RENDERING_VULKAN */