#1 fix unhsq_stsp tool

[Stas Sergeev]

Hi.

I've just noticed that the unhsq code I posted to some
forum 4 years ago, is here in the repository - that's the
good news. :)
The bad one is that it got broken by this:
http://sourceware.org/bugzilla/show_bug.cgi?id=12518
Attached is the fix.
I also added some sanity checks and more comments.
Note that the pre-built unhsq_linux binary is unaffected,
as it has the old memcpy() inlined into the binary.

[Stas Sergeev]

the fix