Fix memory leaks in JNI native code. (#10029)

This commit fixes a couple of minor, host-side memory leaks
in the JNI native code. The objects in question did not need
to go on the heap. They have, in this commit, been switched to 
stack objects.

Authors:
  - MithunR (https://github.com/mythrocks)

Approvers:
  - Jason Lowe (https://github.com/jlowe)

URL: #10029

java/src/main/native/src/ColumnVectorJni.cpp

@@ -359,10 +359,10 @@ JNIEXPORT jlong JNICALL Java_ai_rapids_cudf_ColumnVector_hash(JNIEnv *env, jobje
     std::transform(n_cudf_columns.data(), n_cudf_columns.data() + n_cudf_columns.size(),
                    std::back_inserter(column_views),
                    [](auto const &p_column) { return *p_column; });
-    cudf::table_view *input_table = new cudf::table_view(column_views);
+    cudf::table_view input_table{column_views};
 
     std::unique_ptr<cudf::column> result =
-        cudf::hash(*input_table, static_cast<cudf::hash_id>(hash_function_id), seed);
+        cudf::hash(input_table, static_cast<cudf::hash_id>(hash_function_id), seed);
     return reinterpret_cast<jlong>(result.release());
   }
   CATCH_STD(env, 0);

java/src/main/native/src/ColumnViewJni.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019-2021, NVIDIA CORPORATION.
+ * Copyright (c) 2019-2022, NVIDIA CORPORATION.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -1604,17 +1604,17 @@ JNIEXPORT jlong JNICALL Java_ai_rapids_cudf_ColumnView_bitwiseMergeAndSetValidit
     std::transform(n_cudf_columns.data(), n_cudf_columns.data() + n_cudf_columns.size(),
                    std::back_inserter(column_views),
                    [](auto const &p_column) { return *p_column; });
-    cudf::table_view *input_table = new cudf::table_view(column_views);
+    cudf::table_view input_table{column_views};
 
     cudf::binary_operator op = static_cast<cudf::binary_operator>(bin_op);
     switch (op) {
       case cudf::binary_operator::BITWISE_AND: {
-        auto [new_bitmask, null_count] = cudf::bitmask_and(*input_table);
+        auto [new_bitmask, null_count] = cudf::bitmask_and(input_table);
         copy->set_null_mask(std::move(new_bitmask), null_count);
         break;
       }
       case cudf::binary_operator::BITWISE_OR: {
-        auto [new_bitmask, null_count] = cudf::bitmask_or(*input_table);
+        auto [new_bitmask, null_count] = cudf::bitmask_or(input_table);
         copy->set_null_mask(std::move(new_bitmask), null_count);
         break;
       }