PERLDOC environment variable is abused

[dukeleto]

Reported by Joshua Tolley:

I found myself unable to build just now. The build process would show me a POD
document, I'd exit the pager, and it would show me another. This happened two
or three times, and then the build failed complaining about a missing .pod
file. It turns out this was because I had the PERLDOC environment variable set
to "-i". Unsetting it fixed my build problems.

I hope this is useful to someone ;)

[dukeleto]

Fixed in r44130