Renamed `apply` to `select` to avoid ADL conflict with `std::apply`

Summary:
`std::apply` in C++14 and above is defined with two unrestricted arguments, and
it wins overload resolution in this case.

Reviewers: ilya-biryukov

Subscribers: cfe-commits, ymandel

Tags: #clang

Differential Revision: https://reviews.llvm.org/D62150

llvm-svn: 361170