Add perf-tests for CUMSUM

tests/test-backend-ops.cpp

@@ -8071,6 +8071,12 @@ static std::vector<std::unique_ptr<test_case>> make_test_cases_perf() {
         }
     }
 
+    for (auto nrows : {1, 4, 8, 16}) {
+        for (auto cols : {128, 1024, 4096, 8192, 16384, 32768, 65536, 131072, 200000, 2000000}) {
+            test_cases.emplace_back(new test_cumsum(GGML_TYPE_F32, {cols, nrows, 1, 1}));
+        }
+    }
+
     return test_cases;
 }