Fix a couple of SDL 2.0.20 build issues on Windows.

Builds and passes tests with Debug, but RelWithDebInfo fails to link.
Not a priority.

Author: Tom Seddon

src/b2/b2.cpp

@@ -910,7 +910,9 @@ static bool InitSystem(
 
     if (options.enable_high_dpi) {
 #if SYSTEM_WINDOWS
+#ifdef SDL_HINT_WINDOWS_DPI_AWARENESS
         SDL_SetHint(SDL_HINT_WINDOWS_DPI_AWARENESS, "permonitorv2");
+#endif
 #endif
     }
 

src/b2/dear_imgui.cpp

@@ -273,7 +273,7 @@ bool ImGuiStuff::Init(ImGuiConfigFlags extra_config_flags) {
 
         SDL_SysWMinfo wm_info;
         SDL_VERSION(&wm_info.version);
-        SDL_GetWindowWMInfo(window, &wm_info);
+        SDL_GetWindowWMInfo(m_window, &wm_info);
 
         ImGuiViewport *main_vp = ImGui::GetMainViewport();
         main_vp->PlatformHandleRaw = wm_info.info.win.window;