libblkid: fix integer overflows in HFS+ offset calculations

libblkid: fix integer overflows in HFS+ offset calculations

Two 32-bit multiplications using on-disk values can overflow:

 - leaf_node_head (uint32_t) * leaf_node_size (uint16_t) used to
   calculate leaf_block; overflow produces a wrong block number,
   causing reads from incorrect offsets.

 - embed_first_block (uint16_t) * alloc_block_size (uint32_t) used to
   calculate the embedded HFS+ volume offset; overflow truncates the
   result, again causing reads from wrong offsets.

Fix by widening leaf_block and off to uint64_t and casting
multiplication operands.  Bogus results from crafted images are then
safely rejected by blkid_probe_get_buffer() bounds checking and
the extent loop exhaustion.

Signed-off-by: Karel Zak <kzak@redhat.com>