GitLab

this includes defining an example logutils function for
aggregating null records into a single shared null record (needed
for darshan-merge utility)

This is needed to distinguish between log files generated with
the same job id (i.e., for jobs that have multiple steps)

This function can be called by modules to allow FS-specific
modules to gather data for a given file path/file descriptor.
Currently integrated into POSIX and STDIO modules.

- remaining items are tracked in gitlab issues

- untested

There are cases where lustre stripe info is not available the
first time a given file is opened (e.g., when using the
llapi_file_create call). So, now we call into the lustre module
every time a file is opened to give the module a chance to gather
data.

some bugs were causing the regression tests to fail when using
LD_PRELOAD instrumentation method

- eliminated 110 SLOC
- untested

fixed bugs that prevented record names from mapping to file systems in darshan-util; also fixed thread safety and deadlock issues

A common record comparision/sort routine is now defined in
darshan-common which can be used by any modules with fixed-length
records and whose records first field is the darshan_base_record.
The comparison was also updated to sort secondarily by darshan
record identifier to resolve a potential bug in the way we have
traditionally sorted the records.

rather than using 'begin_shutdown', 'get_output_data', and
'shutdown', we combine all three into one shutdown routine.