romio/gpfs: fixed compilation

- stat64 not available on all platforms.  use stat() instead: at least
  on linux glibc will do the right thing under the hood.

Change-Id: Ic0bc1c9cf0b141ea7aacb4468ce90146e6b0d1ce
Signed-off-by: Rob Latham <[email protected]>

Author: Oblomov, Sergey

src/mpi/romio/adio/ad_gpfs/ad_gpfs_open.c

@@ -114,9 +114,9 @@ void ADIOI_GPFS_Open(ADIO_File fd, int *error_code)
 
         MPI_Comm_rank(fd->comm, &rank);
         if ((rank == fd->hints->ranklist[0]) || (fd->comm == MPI_COMM_SELF)) {
-            struct stat64 gpfs_statbuf;
+            struct stat gpfs_statbuf;
             /* Get the (real) underlying file system block size */
-            rc = stat64(fd->filename, &gpfs_statbuf);
+            rc = stat(fd->filename, &gpfs_statbuf);
             if (rc >= 0) {
                 fd->blksize = gpfs_statbuf.st_blksize;
                 DBGV_FPRINTF(stderr, "Successful stat '%s'.  Blocksize=%ld\n",