fixed compilation error under linux

modules/gpu/src/element_operations.cpp

@@ -654,11 +654,9 @@ void cv::gpu::multiply(const GpuMat& src1, const GpuMat& src2, GpuMat& dst, doub
 
 namespace
 {
-    bool isIntScalar(Scalar sc)
+    inline bool isIntScalar(Scalar sc)
     {
-        Scalar_<int> isc(sc);
-
-        return sc.val[0] == isc.val[0] && sc.val[1] == isc.val[1] && sc.val[2] == isc.val[2] && sc.val[3] == isc.val[3];
+        return sc.val[0] == static_cast<int>(sc.val[0]) && sc.val[1] == static_cast<int>(sc.val[1]) && sc.val[2] == static_cast<int>(sc.val[2]) && sc.val[3] == static_cast<int>(sc.val[3]);
     }
 }
 

modules/gpu/src/gftt.cpp

@@ -153,7 +153,7 @@ void cv::gpu::GoodFeaturesToTrackDetector_GPU::operator ()(const GpuMat& image,
 
                 tmp2.push_back(p);
 
-                if (maxCorners > 0 && tmp2.size() == maxCorners)
+                if (maxCorners > 0 && tmp2.size() == static_cast<size_t>(maxCorners))
                     break;
             }
         }

modules/gpu/src/pyrlk.cpp

@@ -83,8 +83,6 @@ void cv::gpu::PyrLKOpticalFlow::calcSharrDeriv(const GpuMat& src, GpuMat& dIdx,
     ensureSizeIsEnough(src.size(), CV_MAKETYPE(CV_16S, cn), dx_calcBuf_);
     ensureSizeIsEnough(src.size(), CV_MAKETYPE(CV_16S, cn), dy_calcBuf_);
 
-    const int colsn = src.cols * cn;
-
     calcSharrDeriv_gpu(src, dx_calcBuf_, dy_calcBuf_, dIdx, dIdy, cn);
 }