dev-lang/ghc: simplify live ebuild update (always run get / pull)

Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>
dev-lang/ghc: tune happy's lower bound

Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>
dev-lang/ghc: drop experimental USE=shared (broken currently)

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