zsh: Re-enable global rc files

I am not sure why I ever disabled them, but this goes way back to the
very first commit. Since some packages rely on /etc/profile.d/ to add
their location to PATH I want /etc/zsh/zprofile to source these. On my
current Manjaro machine it contains just this line:

    emulate sh -c 'source /etc/profile'

.config/zsh/.zshenv

@@ -1,4 +1,2 @@
-setopt NO_GLOBAL_RCS
-
 # Has to be exported for every pts again so we cannot put this in zprofile
 export GPG_TTY="$TTY"