Fix memleak in sr_gdb_thread_parse error path

Closes #152.

Signed-off-by: Martin Milata <mmilata@redhat.com>
Merge pull request #153 from abrt/gh152-memleak

Fix memleak in sr_gdb_thread_parse error path

Closes #152.

Signed-off-by: Martin Milata <mmilata@redhat.com>