Split bdev into modules: lxczfs

Split bdev into modules: lxczfs

The functions:

	- zfs_clone();
	- zfs_clonepaths();
	- zfs_create();
	- zfs_destroy();
	- zfs_detect();
	- zfs_list_entry();
	- zfs_mount();
	- zfs_umount();

move from bdev.c to lxczfs.{c,h}. All functions previously declared as static
become public.

Adapt Makefile.am to include lxczfs.{c,h}.

The structs:

	- struct bdev; /* defined in bdev.h */
	- struct bdev_specs; /* defined in lxccontainer.h */
	- struct lxc_conf; /* defined conf.h */

are forward declared/put as incomplete types into lxczfs.h as the functions
associated with zfs need access to it.

Minor changes:

	- Use exit(EXIT_FAILURE) instead of exit(1).
	- Use brackets around else {} if the if {} did:
		I.e. instead of:

			if {
				// do one;
				// do two;
			} else
				// do three;

		use:

			if {
				// do one;
				// do two;
			} else {
				// do three;
			}
	- Instead of declaring char pointers and arrays on the same line, i.e.:

		char arr[len], *p;

	  do:

		char arr[len];
		char *p;

	  which makes intentions a lot clearer.

	- Since we require c99 anyway, use finer-grained scoping by declaring
	  variables where they are needed instead of simply at the top.

Signed-off-by: Christian Brauner <christian.brauner@mailbox.org>