[util] Set deviceLossOnFocusLoss for Assassin's Creed 2 (#3763)

Makes it not crash on alt tab using at least Proton. 
Windows will still have issues with alt tab.

src/util/config/config.cpp

@@ -840,6 +840,11 @@ namespace dxvk {
      * Works around alt tab OOM crash           */
     { R"(\\SkyDrift\.exe$)" , {{
       { "d3d9.allowDirectBufferMapping",    "False" },
+    }} },
+     /* Assassin's Creed 2                      *
+     *  Helps alt tab crash on Linux            */
+    { R"(\\AssassinsCreedIIGame\.exe$)" , {{
+      { "d3d9.deviceLossOnFocusLoss",       "True" },
     }} },
     /* Sonic CD                                */
     { R"(\\soniccd\.exe$)", {{