.zshrc: Simplify config on Darwin by using gnubin paths

Homebrew creates gnubin paths where the GNU versions of utils are
not prefixed with "g", so you can call them regularly, like ls and
cp, etc.

.zshrc

@@ -37,23 +37,10 @@ if [[ "$OSTYPE" =~ ^darwin.*$ ]]; then
     # pass needs umount and diskutil, which are in /sbin and /usr/sbin
     PATH=$PATH:/sbin:/usr/sbin
 
-    # use homebrew's GNU coreutils (prefixed with 'g')
+    # use some GNU stuff from homebrew: coreutils findutils gnu-sed
     # requires at least: coreutils findutils gnu-sed
-    alias du='gdu'
-    alias ls='gls -F --color=auto'
-    alias df='gdf'
-    alias rm='grm'
-    alias cp='gcp'
-    alias mv='gmv'
-    alias mkdir='gmkdir'
-    alias rmdir='grmdir'
-    alias chmod='gchmod'
-    alias chown='gchown'
-    alias ln='gln'
-    alias find='gfind'
-    alias sed='gsed'
-    alias dircolors='gdircolors'
-    alias sort='gsort'
+    PATH=/opt/brew/opt/coreutils/libexec/gnubin:/opt/brew/opt/findutils/libexec/gnubin:/opt/brew/opt/gnu-sed/libexec/gnubin:$PATH
+
     alias grep='ggrep'
 
     # If BasicTeX installation exists, add it to PATH
@@ -61,10 +48,10 @@ if [[ "$OSTYPE" =~ ^darwin.*$ ]]; then
     [[ -d /usr/local/texlive/2015basic/bin/x86_64-darwin ]] && PATH=$PATH:/usr/local/texlive/2015basic/bin/x86_64-darwin
 
 elif [[ "$OSTYPE" =~ ^linux.*$ ]]; then
-    # aliases
-    alias ls='ls -F --color=auto'
+    # noop
 fi
 
+alias ls='ls -F --color=auto'
 alias less='less -R' # preserves colors in GNU coreutils' `less`
 
 # solarized dircolors