fix(build): Add remote function benchmark under benchmark flags

The remote function benchmarks are built without checking if the benchmark
utilities are being built. These are only built if certain flags are set.

This causes upstream issues in Prestissimo because there remote functions
are being built but the benchmarks are not.

PR introducing the breaking change:
facebookincubator#11539

velox/functions/remote/CMakeLists.txt

@@ -16,4 +16,6 @@ add_subdirectory(if)
 add_subdirectory(client)
 add_subdirectory(server)
 add_subdirectory(utils)
+if(${VELOX_ENABLE_BENCHMARKS})
 add_subdirectory(benchmarks)
+endif()