housekeeping: remove unused array

the "report an error" macros defined an array that was not used.
more tolerant of whitepace in hintfile

If a hintfile contains e.g. cb_buffer_size = 1234, IOR will try to set
the hint "cb_buffer_size " (note trailing space), a hint that no MPI
implementation actually supports.
A more MPI-IO friendly remove file

MPI-IO allows prefxing file names with something-something: (e.g. pvfs2:
or bglockless:). These prefixed file names, however, do not make sense
to posix calls like access().  So, if we must use access(), strip the
prefix first.