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 <giles@thaumas.net>
2 jobs for sharedbook-free in 1 minute and 46 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Build
passed #11430
docker
autoconf

00:01:46

passed #11431
docker
cmake

00:00:36