Removing 64-bit workaround text from chpldirent.h

When first implementing chpldirent.h as a helper header
in the test/studies/filerator/ directory, I had to put
in a bunch of #ifdef logic to mimic what was happening
on Crays in order to get it working with all PrgEnv's.
It seems to be that this was related to the #define of
_FILE_OFFSET_BITS in sys_basic.h, and that now that
that's commented out, this logic is no longer needed,
so I'm removing it.

I tested this by testing the filerator module on Cray HW
with the four Cray PrgEnvs.  The only failures were the
globberator.chpl runs, which seem to fail even without
the change.
Merge pull request #417 from bradcray/fix-glob-for-cce

Removing 64-bit workaround text from chpldirent.h

When first implementing chpldirent.h as a helper header
in the test/studies/filerator/ directory, I had to put
in a bunch of #ifdef logic to mimic what was happening
on Crays in order to get it working with all PrgEnv's.
It seems to be that this was related to the #define of
_FILE_OFFSET_BITS in sys_basic.h, and that now that
that's commented out, this logic is no longer needed,
so I'm removing it.

I tested this by testing the filerator module on Cray HW
with the four Cray PrgEnvs.  The only failures were the
globberator.chpl runs, which seem to fail even without
the change.