Fix ccache compiler aliases being first in PATH

Add ccache symlink directory to start of PATH, this must be after
`typeset -U PATH` because on macOS this reorders the list so ccache's
symlinks will no longer be at the start of PATH rendering it unusable.

zshenv

@@ -21,9 +21,6 @@ PATH=$HOME/.local/bin:$PATH
 MANPATH=$HOME/.local/share/man:$MANPATH
 INFOPATH=$HOME/.local/share/info:$INFOPATH
 
-# Add ccache to the PATH if present
-[ -f /usr/bin/ccache ] && PATH=/usr/lib/ccache:$PATH
-
 # Use ~/.local for pip installs on macOS
 [ "`uname`" = "Darwin" ] && export PYTHONUSERBASE=$HOME/.local