[arch-haskell] Enabling profiling (-p) option for AUR packages

[Linus Arver]

Hello all,

The wiki page has been updated to reflect the use of the new
PKGBUILD_HASKELL_ENABLE_PROFILING environment variable:

    https://wiki.archlinux.org/index.php/Haskell_package_guidelines

So define that variable if you want to enable profiling builds for all
of your Haskell AUR packages (as they are updated with the newer
cabal2arch version 1.1+).

-Linus