gcc.patch is from a working source tarball that bricewge posted on broadcom-wl-dkms, but I found the patch works for the
broadcom-wl as well.
The broadcom-wl (AUR) module does not build against linux kernel
3.14.2, the latest update in Arch.
To apply the patch, download the broadcom-wl.tar.gz, and unpack it somewhere.
tar -xvzf broadcom-wl.tar.gz
PKGBUILD in that directory with the one that's part of this gist.
Then, put the
gcc.patch into the same directory as the
makepkg -s to build the
broadcom-wl module should now be fine.