fixed report render difference between os x and linux

- fixed sloppy order-of-operations error by adding parens
- switched from struct literal construction of timeval to setting members after
  declaration.  The former seems scary when considering portability.
reduced max report histogram bars to 100
report histogram is now condensed more precisely

previously the time histogram would only condense by integer factors, so with a
bar max of 100, 199 bars would be acceptable.  Now condensing is done with a
double factor for better granularity