how to fix this error

i want to install the leveldb release mode

-- git Version: v1.5.3-7d0d9061
-- Version: 1.5.3
-- Performing Test HAVE_THREAD_SAFETY_ATTRIBUTES -- failed to compile
-- Performing Test HAVE_STD_REGEX -- success
-- Performing Test HAVE_GNU_POSIX_REGEX -- failed to compile
-- Performing Test HAVE_POSIX_REGEX -- success
-- Performing Test HAVE_STEADY_CLOCK -- success
-- Configuring done
-- Generating done
-- Build files have been written to: /Users/haseung-won/leveldb_release1/build
Consolidate compiler generated dependencies of target leveldb
[ 35%] Built target leveldb
Consolidate compiler generated dependencies of target leveldbutil
[ 37%] Built target leveldbutil
Consolidate compiler generated dependencies of target gtest
[ 39%] Built target gtest
Consolidate compiler generated dependencies of target gtest_main
[ 41%] Built target gtest_main
Consolidate compiler generated dependencies of target gmock
[ 43%] Built target gmock
Consolidate compiler generated dependencies of target leveldb_tests
[ 66%] Built target leveldb_tests
Consolidate compiler generated dependencies of target c_test
[ 68%] Built target c_test
Consolidate compiler generated dependencies of target env_posix_test
[ 70%] Built target env_posix_test
Consolidate compiler generated dependencies of target benchmark
[ 71%] Building CXX object third_party/benchmark/src/CMakeFiles/benchmark.dir/complexity.cc.o
/Users/haseung-won/leveldb_release1/third_party/benchmark/src/complexity.cc:85:10: error: variable 'sigma_gn' set but not used [-Werror,-Wunused-but-set-variable]
double sigma_gn = 0.0;
^
1 error generated.
make[2]: *** [third_party/benchmark/src/CMakeFiles/benchmark.dir/complexity.cc.o] Error 1
make[1]: *** [third_party/benchmark/src/CMakeFiles/benchmark.dir/all] Error 2
make: *** [all] Error 2