[WIP] fix leaks

Leaking much less memory, but still have one left in `sphia_new`:

```
==15343== 48 bytes in 1 blocks are definitely lost in loss record 1 of 17
==15343==    at 0x4C29DB4: calloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==15343==    by 0x504F8EE: pthread_cond_signal@GLIBC_2.2.5 (old_pthread_cond_signal.c:37)
==15343==    by 0x4E3760D: sp_open (in /usr/local/lib/libsophia.so.1)
==15343==    by 0x4042A7: sphia_new (in /home/stephen/libsphia/sphia-test)
==15343==    by 0x40183F: test_simple_count (in /home/stephen/libsphia/sphia-test)
==15343==    by 0x401B0F: test_count (in /home/stephen/libsphia/sphia-test)
==15343==    by 0x400FE6: main (in /home/stephen/libsphia/sphia-test)
```