Runs make twice while building ghc

Due to a known bug in ghc, make will always fail with `expectJust
initTcInteractive` the first time you try to build it
MAKEFLAGS from /etc/makepkg.conf

Rather than setting them ourselves, we take the MAKEFLAGS from
the systemwide configuration (at least on Arch)
Merge pull request #1 from atondwal/master

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