time(1) has no effect when used on a built-in

[avidseeker <avidseeker@xxxxxxxxxxx>]

Not sure if this is intentional, but looks like a bug. Compare with bash 
output:

```
$ zsh -c 'time echo yes'
yes
$ bash -c 'time echo yes'
yes

real    0m0.000s
user    0m0.000s
sys     0m0.000s

$ zsh -c 'time command -v yes'
/usr/bin/yes
$ bash -c 'time command -v yes'
/usr/bin/yes

real    0m0.000s
user    0m0.000s
sys     0m0.000s
```

Avid