profiles/package.mask: unmask ghc-7.8 and friends

Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>
dev-lang/ghc-7.8.3: properly keyword on x86/amd64

Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>
dev-haskell/haddock: properly keyword on x86/amd64

Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>