dev-lang/ghc-7.8.4: drop -Os from build flags as it inhibits vital reorder optimisations

Signed-off-by: Sergei Trofimovich <siarheit@google.com>
dev-haskell/rasterific: allow juicypixels-3.2

Signed-off-by: Sergei Trofimovich <siarheit@google.com>