avl64: export avl64_firstino / avl64_firstino from avl64.h

avl64: export avl64_firstino / avl64_firstino from avl64.h

These are flagged by the sparse checker as possibly static.
They are actually not used at this point; avl64.c has a few unused
functions and/or ones that could be made static, but for now just silence
the warnings, and save deeper surgery for later.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>