'make perf': Unbreak by porting over 'make test' harness changes.
'make perf': Unbreak by porting over 'make test' harness changes.

In particular, tests were relying on the harness to provide a sandbox working
directory, but the perf harness wasn't providing that.

m0vie/zsh-syntax-highlighting,danielshahaf/zsh-syntax-highlighting,stuha/wbr-zsh,zsh-users/zsh-syntax-highlighting,joshuarubin/dotfiles,P71/zsh-syntax-highlighting,joshuarubin/dotfiles,zsh-users/zsh-syntax-highlighting,m0vie/zsh-syntax-highlighting,danielshahaf/zsh-syntax-highlighting-debian,danielshahaf/zsh-syntax-highlighting,joshuarubin/dotfiles,x-way/zsh-syntax-highlighting,phy1729/zsh-syntax-highlighting,psprint/zsh-syntax-highlighting,danielshahaf/zsh-syntax-highlighting-debian,P71/zsh-syntax-highlighting,phy1729/zsh-syntax-highlighting,x-way/zsh-syntax-highlighting,psprint/zsh-syntax-highlighting,joshuarubin/dotfiles