New feature: collect Pthread IDs into DXT records

[wkliao]

This PR enables Darshan to collect pthread IDs (type of an unsigned long) into DXT records.

See #1066 for more discussion. Note that #1066 also mentions an extra annotation, in addition to pthread ID, but this PR only adds pthread IDs, without the extra annotation. Adding the extra annotations will be in a separate PR.

An example of text output from darshan-dxt-parser is shown below.
It has "Pthread-ID" added as the right-most column.

# Module    Rank  Wt/Rd  Segment          Offset          Length    Start(s)      End(s)     Pthread-ID
 X_POSIX       2  write        0              16               8      0.0022      0.0022     140498826330816

For older versions:

# Module    Rank  Wt/Rd  Segment          Offset          Length    Start(s)      End(s)   [OST]     Pthread-ID
 X_POSIX       0  write        0            2048          262144      0.0300      0.0331   [106]     -1

[wkliao]

HI, @GueroudjiAmal and @infispiel

@carns suggested me to reach out to you for an advise about this PR.

As the text outputs generated from darshan-dxt-parser is organized into columns, this PR
adds a new column at the end, showing the pthread IDs. There can be two options for
presenting its values. One is to use the ID returned from a call to pthread_self() which may
be a type of unsigned long integer or a memory pointer address depending on the systems.
The other option is a number relative to the total number of threads per rank. Please let us
know which one works best for you.

Below shows two examples outputs. Note this only affects the outputs of darshan-dxt-parser.
The darshan log files (i.e. the binary files) still store the pthread IDs returned from pthread_self().

Option 1:

# DXT, rank: 1, hostname: acfs.ece.northwestern.edu
# DXT, write_count: 4, read_count: 3
# DXT, mnt_pt: /homes, fs_type: autofs
# Module    Rank  Wt/Rd  Segment          Offset          Length    Start(s)      End(s)   Pthread-ID
 X_POSIX       1  write        0              30              30      0.0017      0.0017   139906430563008
 X_POSIX       1  write        1             200              10      0.0019      0.0020   139906339825408
 X_POSIX       1  write        2             180              10      0.0020      0.0020   139906356610816
 X_POSIX       1  write        3             190              10      0.0020      0.0020   139906348218112
 X_POSIX       1   read        0              70              10      0.0019      0.0019   139906348218112
 X_POSIX       1   read        1              60              10      0.0019      0.0019   139906356610816
 X_POSIX       1   read        2              80              10      0.0019      0.0019   139906339825408

and option 2:

# DXT, rank: 1, hostname: acfs.ece.northwestern.edu
# DXT, write_count: 4, read_count: 3
# DXT, mnt_pt: /homes, fs_type: autofs
# Number of threads: 4
# Module    Rank  Wt/Rd  Segment          Offset          Length    Start(s)      End(s)   Pthread-ID
 X_POSIX       1  write        0              30              30      0.0022      0.0022      0
 X_POSIX       1  write        1             180              10      0.0023      0.0024      1
 X_POSIX       1  write        2             200              10      0.0024      0.0024      2
 X_POSIX       1  write        3             190              10      0.0024      0.0024      3
 X_POSIX       1   read        0              60              10      0.0023      0.0023      1
 X_POSIX       1   read        1              70              10      0.0024      0.0024      3
 X_POSIX       1   read        2              80              10      0.0024      0.0024      2

[GueroudjiAmal]

Hi,
In my opinion it is better to have the pthread ID returned by pthread_self() , to further trace the thread/IO mapping and eventually correlate that with other thread related tasks.