Avoid detecting dublicate CUDA archs

cmake/checks/OpenCVDetectCudaArch.cu

-#include <stdio.h>
+#include <iostream>
+#include <sstream>
+#include <list>
+
 int main()
 {
+    std::ostringstream arch;
+    std::list<std::string> archs;
+
     int count = 0;
-    if (cudaSuccess != cudaGetDeviceCount(&count)){return -1;}
-    if (count == 0) {return -1;}
+    if (cudaSuccess != cudaGetDeviceCount(&count)){ return -1; }
+    if (count == 0) { return -1; }
     for (int device = 0; device < count; ++device)
     {
         cudaDeviceProp prop;
-        if (cudaSuccess != cudaGetDeviceProperties(&prop, device)){ continue;}
-        printf("%d.%d ", prop.major, prop.minor);
+        if (cudaSuccess != cudaGetDeviceProperties(&prop, device)){ continue; }
+        arch << prop.major << "." << prop.minor;
+        archs.push_back(arch.str());
+        arch.str("");
     }
+    archs.unique(); #Some devices might have the same arch
+    for (std::list<std::string>::iterator it=archs.begin(); it!=archs.end(); ++it)
+        std::cout << *it << " ";
     return 0;
 }