ghc-7.6.3.ebuild: fix building on systems where libdir differs from the one we have built GHC

Reported-by: tamiko
Reported-by: Christoph Junghans
Gentoo-bug: http://bugs.gentoo.org/476998

Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>
Add exceptions for lens-9999
lens-9999 now requires exceptions
copy missing exceptions tests, loosen QuickCheck dep