implement internal darshan-core fprintf routine

Closes #251

See merge request !29

bugfix to enable compilation on 32-bit platforms (resolves #252)

Closes #252

See merge request !26

add wrapper for __open_2 function call

Closes #253

See merge request !28

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 darshan/darshan!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