old libdaemon sets wrong umask for infinoted

[ben]

In some prior version of libdaemon, the daemon_fork() call set the umask of the background process to 0777, and the documentation still claims this is the case. Our file storage backend consequently creates files it cannot read again and subdirectories in which it cannot create more files.

At least Ubuntu apparently still ships that version, so we either need to figure out just when libdaemon stopped doing that and depend on a more recent version, or just call umask(0077); in the child process manually.

[ben]

Inserted explicit umask(0077) call in branches master (86e18b52...) and libinfinity-0.4 (a3e11e46...), for now.