crush: recalculate straw scalers during a reweight

The crushtool --reweight function triggers a fresh calculation of bucket
weights so that they are always the sum of the item weights.  In the
straw bucket case, the weights were updated but the corresponding straw
scalers were not being recalculated.  The result is that there was not
effect on placement in adjusted buckets until the next time a bucket item's
weight was adjusted.

Backport: giant, firefly
Signed-off-by: Sage Weil <sage@redhat.com>
crushtool/CrushTester: output utilization even with 1 batch

Signed-off-by: Sage Weil <sage@redhat.com>
crush/CrushTester: do not dump raw outputs

This makes --show-utilization and --show-statistics unusable.

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