Fix build with older versions of libaio.h

* configure.ac: When libaio.h is available, check for
struct iocb.u.c.flags, IO_CMD_PWRITE and IO_CMD_PWRITEV.
* desc.c (print_common_flags): Check for HAVE_STRUCT_IOCB_U_C_FLAGS.
(sys_io_submit): Check for HAVE_DECL_IO_CMD_PWRITE and
HAVE_DECL_IO_CMD_PWRITEV.
2 files changed