Fix printf in __zplug::job::handle::wait

[kba]

Since arguments to __zplug::io::print::f are two integers, do not prepend [zplug]. Also, use the proc_states associative array for length, not the array repos.

Without these changes, I get output like this:

[zplug] Start to [zplug] update printf: [zplug] 10: expected a numeric value
0 plugins [zplug] in parallel

 ⠙  Updating...           zsh-users/zsh-completions
 ⠹  Updating...           zsh-users/zsh-completions-completion
 ⠸  Updating...           zsh-users/zsh-completions-completion
 ⠼  Updating...           zsh-users/zsh-completions-completionch
[...]

[zplug] Finished: printf: [zplug] 0: expected a numeric value
0/printf: [zplug] 10: expected a numeric value
0 plugins

[kba]

Sorry to bump, but I've run into this on every (linux) box I deployed my zsh-config to. Is nobody else having this issue?

Edit: Seems like the same issue as #419

[babarot]

LGTM

[sudoforge]

Is there any particular reason that this hasn't been merged?

[kba]

Sorry to bump yet again but I run into this consistently.

[kba]

@b4b4r07 Sorry, another bump, since you released a new version last week. Please consider including this PR in the next release, it still happens for me on Ubuntu 17.10

[ghost]

LGTM
@b4b4r07 @NigoroJr @39e これはいつマージされますか？

[babarot]

Hi, all. Sorry for late response. I merged this PR now. Sorry for inconvenience.