Fix build with <linux/loop.h> from 2.6.18 kernel headers

* configure.ac: Check for LO_FLAGS_AUTOCLEAR and LO_FLAGS_PARTSCAN
declarations.
* loop.c (loop_flags_options): Use LO_FLAGS_AUTOCLEAR and
LO_FLAGS_PARTSCAN only when appropriate declarations are available.
(loop_ioctl): Use LOOP_SET_CAPACITY only when it is defined.
2 files changed