[scripts] fix ninja build log permissions (#489)
[scripts] fix ninja build log permissions (#489)

This commit ensures ninja has permission to access the log files
(i.e. .ninja_log and .ninja_deps)
bukepo/borderrouter,openthread/ot-br-posix,openthread/borderrouter,openthread/borderrouter,openthread/ot-br-posix,jwhui/borderrouter,openthread/borderrouter,jwhui/borderrouter,openthread/borderrouter,openthread/ot-br-posix,jwhui/borderrouter,openthread/ot-br-posix,jwhui/borderrouter,bukepo/borderrouter,openthread/ot-br-posix,jwhui/borderrouter,bukepo/borderrouter,openthread/ot-br-posix,openthread/borderrouter,bukepo/borderrouter,bukepo/borderrouter,openthread/borderrouter