[util] Enable longMad for Tomb Raider Legend

Since the enablement of invariant position by default the game suffers from white flickers on characters when you use the Next Generation Content option

src/util/config/config.cpp

@@ -593,10 +593,12 @@ namespace dxvk {
     /* Tomb Raider: Legend, Anniversary, Underworld  *
      * Read from a buffer created with:              *
      * D3DPOOL_DEFAULT,                              *
-     * D3DUSAGE_DYNAMIC | D3DUSAGE_WRITEONLY buffer  */
+     * D3DUSAGE_DYNAMIC | D3DUSAGE_WRITEONLY buffer. *
+     * Legend flickers with next gen content option. */
     { R"(\\(trl|tra|tru)\.exe$)", {{
       { "d3d9.cachedDynamicBuffers",        "True" },
       { "d3d9.maxFrameRate",                "60" },
+      { "d3d9.longMad",                     "True" },
     }} },
     /* Everquest                                 */
     { R"(\\eqgame\.exe$)", {{