add condition to skip unmapping for internally allocated host memory. this should fix map_unmap_counting UMat test.

modules/core/src/ocl.cpp

@@ -4572,6 +4572,8 @@ public:
                     else
                     {
                         // CL_MEM_USE_HOST_PTR (nothing is required) and OTHER cases
+                        if (u->flags & UMatData::USER_ALLOCATED)
+                        {
                             cl_int retval = 0;
                             void* data = clEnqueueMapBuffer(q, (cl_mem)u->handle, CL_TRUE,
                                 (CL_MAP_READ | CL_MAP_WRITE),
@@ -4581,6 +4583,7 @@ public:
                             CV_OclDbgAssert(clFinish(q) == CL_SUCCESS);
                         }
                     }
+                }
                 u->markHostCopyObsolete(false);
             }
 #ifdef HAVE_OPENCL_SVM