Fix `integer overflow in expression' error

Author: AMDmi3

tools/db_stress.cc

@@ -223,7 +223,7 @@ DEFINE_int32(set_options_one_in, 0,
 DEFINE_int32(set_in_place_one_in, 0,
              "With a chance of 1/N, toggle in place support option");
 
-DEFINE_int64(cache_size, 2 * KB * KB * KB,
+DEFINE_int64(cache_size, 2LL * KB * KB * KB,
              "Number of bytes to use as a cache of uncompressed data.");
 
 DEFINE_uint64(subcompactions, 1,