workaround to compile error and MAKEFLAGS from /etc/makepkg.conf

As Nathan points out, due to a known bug in ghc, you should run make twice in your script when building ghc. (it'll always fail with `expectJust initTcInteractive` the first time you try to build it fresh)

Additional, since we're already somewhat arch-specific, we should source /etc/makepkg.conf to get the makeflags instead of using just -j6 (on my system I use -j12 for example) I was wondering why my load averages were so low before I realized you set -j manually.