configureGPU() should respect given platformID

Related to #2314

libethash-cl/ethash_cl_miner.cpp

@@ -139,6 +139,7 @@ unsigned ethash_cl_miner::getNumDevices(unsigned _platformId)
 }
 
 bool ethash_cl_miner::configureGPU(
+	unsigned _platformId,
 	bool _allowCPU,
 	unsigned _extraGPUMemory,
 	boost::optional<uint64_t> _currentBlock
@@ -149,7 +150,7 @@ bool ethash_cl_miner::configureGPU(
 	// by default let's only consider the DAG of the first epoch
 	uint64_t dagSize = _currentBlock ? ethash_get_datasize(*_currentBlock) : 1073739904U;
 	uint64_t requiredSize =  dagSize + _extraGPUMemory;
-	return searchForAllDevices([&requiredSize](cl::Device const _device) -> bool
+	return searchForAllDevices(_platformId, [&requiredSize](cl::Device const _device) -> bool
 		{
 			cl_ulong result;
 			_device.getInfo(CL_DEVICE_GLOBAL_MEM_SIZE, &result);

libethash-cl/ethash_cl_miner.h

@@ -44,6 +44,7 @@ public:
 	static std::string platform_info(unsigned _platformId = 0, unsigned _deviceId = 0);
 	static void listDevices();
 	static bool configureGPU(
+		unsigned _platformId,
 		bool _allowCPU,
 		unsigned _extraGPUMemory,
 		boost::optional<uint64_t> _currentBlock

libethcore/Ethash.cpp

@@ -418,7 +418,7 @@ bool Ethash::GPUMiner::configureGPU(
 {
 	s_platformId = _platformId;
 	s_deviceId = _deviceId;
-	return ethash_cl_miner::configureGPU(_allowCPU, _extraGPUMemory, _currentBlock);
+	return ethash_cl_miner::configureGPU(_platformId, _allowCPU, _extraGPUMemory, _currentBlock);
 }
 
 #endif