fixed possible compilation error for macos

modules/gpu/src/imgproc.cpp

@@ -1143,7 +1143,7 @@ void cv::gpu::mulSpectrums(const GpuMat& a, const GpuMat& b, GpuMat& c, int flag
 
     typedef void (*Caller)(const PtrStep<cufftComplex>, const PtrStep<cufftComplex>, DevMem2D_<cufftComplex>, cudaStream_t stream);
 
-    static Caller callers[] = { mulSpectrums, mulSpectrums_CONJ };
+    static Caller callers[] = { device::imgproc::mulSpectrums, device::imgproc::mulSpectrums_CONJ };
 
     CV_Assert(a.type() == b.type() && a.type() == CV_32FC2);
     CV_Assert(a.size() == b.size());
@@ -1172,7 +1172,7 @@ void cv::gpu::mulAndScaleSpectrums(const GpuMat& a, const GpuMat& b, GpuMat& c,
     using namespace ::cv::gpu::device::imgproc;
 
     typedef void (*Caller)(const PtrStep<cufftComplex>, const PtrStep<cufftComplex>, float scale, DevMem2D_<cufftComplex>, cudaStream_t stream);
-    static Caller callers[] = { mulAndScaleSpectrums, mulAndScaleSpectrums_CONJ };
+    static Caller callers[] = { device::imgproc::mulAndScaleSpectrums, device::imgproc::mulAndScaleSpectrums_CONJ };
 
     CV_Assert(a.type() == b.type() && a.type() == CV_32FC2);
     CV_Assert(a.size() == b.size());