MAINT-7548 MAINT-7560 use NvidiaOptimusEnablement globally exported var to...

MAINT-7548 MAINT-7560 use NvidiaOptimusEnablement globally exported var to signal desire to use high-performance graphics processor

indra/llrender/llgl.cpp

@@ -2561,5 +2561,10 @@ void LLGLSyncFence::wait()
 #endif
 }
 
-
-
+#if LL_WINDOWS
+// Expose desired use of high-performance graphics processor to Optimus driver
+extern "C" 
+{ 
+    _declspec(dllexport) DWORD NvOptimusEnablement = 0x00000001; 
+}
+#endif
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