Fix debug-blocks assertion where real size didn't match passed size.
Fix debug-blocks assertion where real size didn't match passed size.

This patch fixes an issue where g_slice_free was being called on
memory that was allocated with IdleDNSResultReal, but was being
freed as IdleDNSResult. These two structures are a difference size.
With debug-blocks on it asserts this and aborts.

freedesktop-unofficial-mirror/telepathy__telepathy-idle,freedesktop-unofficial-mirror/telepathy__telepathy-idle,freedesktop-unofficial-mirror/telepathy__telepathy-idle