fix moncommands
fix tree
crush/mapper: clarify numrep vs endpos

Pass numrep (the width of the result) separately from the number of results
we want *this* iteration.  This makes things less awkward when we do a
recursive call (for chooseleaf) and want only one item.

Signed-off-by: Sage Weil <sage@inktank.com>
crush/mapper: pass parent r value for indep call

Pass down the parent's 'r' value so that we will sample different values in
the recursive call when the parent tries multiple times.  This avoids doing
useless work (calling multiple times and trying the same values).

Signed-off-by: Sage Weil <sage@inktank.com>
crush/mapper: new SET_CHOOSE_LEAF_TRIES command

Explicitly control the number of sample attempts, and allow the number of
tries in the recursive call to be explicitly controlled via the rule. This
is important because the amount of time we want to spend looking for a
solution may be rule dependent (e.g., higher for the wide indep pool than
the rep pools).

(We should do the same for the other tunables, by the way!)

Signed-off-by: Sage Weil <sage@inktank.com>