Fix linker error with tablet_replica-test-base.cc on Mac OS

Hit following linker error on Mac OS 10.15.4 which indicates
missing gtest related library.

Undefined symbols for architecture x86_64:
  "kudu::KuduTest::SetUp()", referenced from:
      kudu::tablet::KuduTabletTest::SetUp() in tablet_replica-test-base.cc.o
  "testing::Test::TearDown()", referenced from:
      kudu::tablet::TabletReplicaTestBase::TearDown() in tablet_replica-test-base.cc.o
  "testing::Message::Message()", referenced from:
      kudu::tablet::TabletReplicaTestBase::SetUp() in tablet_replica-test-base.cc.o
  "testing::internal::AssertHelper::AssertHelper(testing::TestPartResult::Type, char const*, int, char const*)", referenced from:
      kudu::tablet::TabletReplicaTestBase::SetUp() in tablet_replica-test-base.cc.o
  "testing::internal::AssertHelper::~AssertHelper()", referenced from:
      kudu::tablet::TabletReplicaTestBase::SetUp() in tablet_replica-test-base.cc.o
  "testing::internal::AssertHelper::operator=(testing::Message const&) const", referenced from:
      kudu::tablet::TabletReplicaTestBase::SetUp() in tablet_replica-test-base.cc.o
  "typeinfo for kudu::KuduTest", referenced from:
      typeinfo for kudu::tablet::KuduTabletTest in tablet_replica-test-base.cc.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make[2]: *** [lib/libtablet_test_util.dylib] Error 1

Added kudu_test_util as suggested by Andrew to fix the linker issue.

Change-Id: Ie5857cc0b3436452b5de5aa85fbffe42fad7dff3
Reviewed-on: http://gerrit.cloudera.org:8080/16038
Tested-by: Kudu Jenkins
Reviewed-by: Andrew Wong <[email protected]>

src/kudu/tablet/CMakeLists.txt

@@ -89,6 +89,7 @@ add_library(tablet_test_util
   tablet_replica-test-base.cc)
 target_link_libraries(tablet_test_util
   kudu_common
+  kudu_test_util
   log_proto
   tablet)