Test p{read,write}64 with offset > 4GB. Since it is not an error for a
successful pread/pwrite call to transfer fewer bytes than requested, we
should check if the return value is -1. No need to close and unlink
temporary file, which is handled by test-skeleton.c.
[BZ #20350]
* posix/tst-preadwrite.c: Renamed to ...
* posix/tst-preadwrite-common.c: This.
(PREAD): Removed.
(PWRITE): Likewise.
(STRINGIFY): Likewise.
(STRINGIFY2): Likewise.
(do_prepare): Make it static and remove function arguments.
(do_test): Likewise.
(PREPARE): Updated.
(TEST_FUNCTION): New.
(name): Make it static.
(fd): Likewise.
(do_prepare): Use create_temp_file.
(do_test): Renamed to ...
(do_test_with_offset): This. Make it static and accept offset.
Properly check return value of PWRITE and PREAD. Return bytes
read. Don't close fd nor unlink name.
* posix/tst-preadwrite.c: Rewrite.
* posix/tst-preadwrite64.c: Likewise.
