Matthew writes:
> PCSX2 requires a more up to date commit for libchdr.
>
> Both flycast and libretro-pcsx-rearmed built and ran with a couple
> chd files I tried using this new version.

huffman_build_lookup_table() changed return type, so this needs a
major bump.

make port-lib-depends-check complains about missing pthread, so I
added it to WANTLIB.

I've committed it with these changes.