2014.2.0.0 on 64-bit Linux: Path component for lib is hardcoded, has to be lib64 on openSUSE

[johanwiden]

The path component for libraries (think /usr/lib versus /usr/lib64) is OS dependent. But it is hardcoded in "hptool/src/GhcDist.hs" and "hptool/src/OS/Posix.hs".

Suggested fix: Make what is now hardcoded as "lib" a parameter that is possible to override with a command option to "platform.sh", in the same way that one can now override prefix with the
--prefix command option.

"lib" is also hardcoded in the script "activate-hs".

[gbaz]

@dagit-- also worth considering. I think we can do this all in scripts with some post-hoc path munging on the tarball unpack...maybe?

this could be a bit tricky, but I ran into it back in the daaay