[LTP] [PATCH v3] Add utime07 test

[Petr Vorel]

Hi Andrea,

merged with Avinesh's RBT (you could have added it yourself, as he added it in
v2 and you changed what he proposed).

Also I dared to slightly change the documentation (added errnos) and fix minor
whitespace.

Thank you!

Kind regards,
Petr