block_bloom_filter: quell warning in release build
block_bloom_filter: quell warning in release build

Saw this when building in release mode.

[687/1584] Building CXX object src/kudu/uti...u_util_exported.dir/block_bloom_filter.cc.o
../../src/kudu/util/block_bloom_filter.cc: In constructor ‘kudu::BlockBloomFilter::BlockBloomFilter(kudu::BlockBloomFilterBufferAllocatorIf*)’:
../../src/kudu/util/block_bloom_filter.cc:93:42: warning: statement has no effect [-Wunused-value]
   DCHECK_NOTNULL(bucket_insert_func_ptr_);
                                          ^
../../src/kudu/util/block_bloom_filter.cc:94:40: warning: statement has no effect [-Wunused-value]
   DCHECK_NOTNULL(bucket_find_func_ptr_);
                                        ^
../../src/kudu/util/block_bloom_filter.cc:95:43: warning: statement has no effect [-Wunused-value]
   DCHECK_NOTNULL(or_equal_array_func_ptr_);
                                           ^

From glog/logging.h:
 You may see warnings in release mode if you don't use the return
 value of DCHECK_NOTNULL. Please just use DCHECK for such cases.

Change-Id: I6fc2e715ea156dea6cb99369d84e6bc3c338fca0
Reviewed-on: http://gerrit.cloudera.org:8080/15478
Tested-by: Kudu Jenkins
Reviewed-by: Adar Dembo <866ca730bfc7f544e3ebce604ceeba4879f23df0@cloudera.com>

helifu/kudu,helifu/kudu,helifu/kudu,helifu/kudu,helifu/kudu,helifu/kudu,helifu/kudu,helifu/kudu,helifu/kudu