OpenCL: fix windows vega and vii

Fix again issues with vega and vii with the latest windows driver.

xmrstak/backend/amd/amd_gpu/gpu.cpp

@@ -334,6 +334,12 @@ size_t InitOpenCLGpu(cl_context opencl_ctx, GpuContext* ctx, const char* source_
 		 */
 		options += " -DOPENCL_DRIVER_MAJOR=" + std::to_string(std::stoi(openCLDriverVer.data()) / 100);
 
+		uint32_t isWindowsOs = 0;
+#ifdef _WIN32
+		isWindowsOs = 1;
+#endif
+		options += " -DIS_WINDOWS_OS=" + std::to_string(isWindowsOs);
+		
 		if(miner_algo == cryptonight_gpu)
 			options += " -cl-fp32-correctly-rounded-divide-sqrt";
 

xmrstak/backend/amd/amd_gpu/opencl/cryptonight.cl

@@ -1361,7 +1361,7 @@ __kernel void Groestl(__global ulong *states, __global uint *BranchBuf, __global
 		states += 25 * BranchBuf[idx];
 
 		ulong State[8] = { 0UL, 0UL, 0UL, 0UL, 0UL, 0UL, 0UL, 0x0001000000000000UL };
-#if defined(__clang__) && !defined(__NV_CL_C_VERSION)
+#if defined(__clang__) && !defined(__NV_CL_C_VERSION) && (IS_WINDOWS_OS != 1)
 		// on ROCM we need volatile for AMD RX5xx cards to avoid invalid shares
 		volatile
 #endif