[ADT] Zip range adapter

This augments the STLExtras toolset with a zip iterator and range
adapter. Zip comes in two varieties: `zip`, which will zip to the
shortest of the input ranges, and `zip_first`, which limits its
`begin() == end()` checks to just the first krange.

Patch by: Bryant Wong <github.com/bryant>

Differential Revision: https://reviews.llvm.org/D23252

llvm-svn: 284035