Need to link boost::chrono in more places now

src/blockchain_db/CMakeLists.txt

@@ -65,6 +65,7 @@ target_link_libraries(blockchain_db
     crypto
     cryptonote_core
     ${Boost_DATE_TIME_LIBRARY}
+    ${Boost_CHRONO_LIBRARY}
     ${Boost_PROGRAM_OPTIONS_LIBRARY}
     ${Boost_SERIALIZATION_LIBRARY}
     ${LMDB_LIBRARY}

src/connectivity_tool/CMakeLists.txt

@@ -42,4 +42,5 @@ target_link_libraries(connectivity_tool
     ${CMAKE_THREAD_LIBS_INIT}
     ${Boost_PROGRAM_OPTIONS_LIBRARY}
     ${Boost_REGEX_LIBRARY}
+    ${Boost_CHRONO_LIBRARY}
     ${Boost_SYSTEM_LIBRARY})

src/miner/CMakeLists.txt

@@ -49,6 +49,7 @@ target_link_libraries(simpleminer
     ${Boost_FILESYSTEM_LIBRARY}
     ${Boost_PROGRAM_OPTIONS_LIBRARY}
     ${Boost_REGEX_LIBRARY}
+    ${Boost_CHRONO_LIBRARY}
     ${Boost_SYSTEM_LIBRARY}
     ${Boost_THREAD_LIBRARY}
     ${CMAKE_THREAD_LIBS_INIT}