Even though Win32 only has one windowing system, it is supported

* Generic code may be looking for the supported window systems even on windows.

renderdoc/driver/gl/gl_replay.cpp

@@ -163,6 +163,8 @@ rdcarray<WindowingSystem> GLReplay::GetSupportedWindowSystems()
   ret.push_back(WindowingSystem::Android);
 #elif ENABLED(RDOC_APPLE)
   ret.push_back(WindowingSystem::MacOS);
+#elif ENABLED(RDOC_WIN32)
+  ret.push_back(WindowingSystem::Win32);
 #endif
 
   return ret;

renderdoc/driver/vulkan/vk_win32.cpp

@@ -109,6 +109,8 @@ void WrappedVulkan::AddRequiredExtensions(bool instance, rdcarray<rdcstr> &exten
     }
     else
     {
+      m_SupportedWindowSystems.push_back(WindowingSystem::Win32);
+
       if(!extensionList.contains(VK_KHR_WIN32_SURFACE_EXTENSION_NAME))
         extensionList.push_back(VK_KHR_WIN32_SURFACE_EXTENSION_NAME);
     }