fix darshan-job-summary reporting spurious total bytes written

See merge request darshan/darshan!25

Fixes #243

Hxhim module

See merge request darshan/darshan!23

the struct alignment is important here, as we are going to read this
struct once to get the fixed values and a second time to fill in the
extra histogram buckets.

this requires a hacked up version of mdhim until there's a real api for
getting this information.

omit outputting with old-style fopen counters

Closes #241

See merge request !22

# Conflicts:
#   ChangeLog

- perf_mbytes is a global used later in pdf generation, do not overwrite
  in stdio output parsing

- these cannot be easily translated into Darshan 3.1.x format
- fixes #241

- resolve warnings
- make format more consistent

we should probably always include logs that contain dxt data in
the example output directory so we can track that module over
releases