[syscheck] fix compiler warnings
[syscheck] fix CID 28505, 28506
[syscheck] fix CID 28429
[syscheck] fix windows build
[syscheck] delete dead code
[syscheck] add nonnull qualifiers
[rootcheck] fix compiler warnings
[rootcheck] fix clang analyzer warnings
[rootcheck] fix CID 28592, by deleting unused function start_rk_daemon()
[rootcheck] fix CID 28593
[rootcheck] fix CID 28440
[rootcheck] fix CID 28477
[rootcheck] fix CID 28449
[util] fix compiler warnings
[util] remove unnecessary strdup
[addagent] fix compiler warnings
[addagent] correct indent
[addagent] fix memory leak
[addagent] fix CID 28507
[addagent] fix CID 28428