Test p{read,write}64 with offset > 4GB

Test p{read,write}64 with offset > 4GB

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.