Fix tests run with make check when using alternative allocators.
The call to free in line 584 of sharedbook.c mismatches the _ogg_calloc call used to allocated that data in line 216.
This causes make check to fail when alternative allocators are used, e.g. the xmm_malloc family of allocators used with the Lancer optimizations.
Signed-off-by: Ralph Giles email@example.com