updated build system

cmake/libraries/rocksdb.cmake

@@ -9,6 +9,8 @@ if(PROJECT_ENABLE_ROCKSDB)
       URL ${PROJECT_3RD_PARTY_DIR}/rocksdb-${ROCKSDB_VERSION}.tar.gz
       URL_HASH SHA256=${ROCKSDB_HASH}
       LIST_SEPARATOR |
+      BUILD_COMMAND 
+        ${CMAKE_COMMAND} --build . -- -j$ENV{CMAKE_BUILD_PARALLEL_LEVEL}
       CMAKE_ARGS ${PROJECT_EXTERNAL_CMAKE_FLAGS}
         -DBUILD_SHARED_LIBS=OFF
         -DBUILD_STATIC_LIBS=ON
@@ -31,4 +33,4 @@ if(PROJECT_ENABLE_ROCKSDB)
 
     list(APPEND PROJECT_DEPENDENCIES rocksdb_project)
   endif()
-endif()
+endif()