autoconf: fix pio checks name
The autoconf macro to perform the positional i/o checks was misnamed as
hpux checks (since there happens to be a specific check for hpux at the
top of the macro). Change the macro name and m4 file name to be more
accurately named.
Change-Id: Ib85728fbfe67930cb5f9f1f0e34f7aa1195fdfc6
Reviewed-on: https://gerrit.openafs.org/12992
Reviewed-by: Michael Meffie <mmeffie@sinenomine.net>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
Tested-by: BuildBot <buildbot@rampaginggeek.com>