[Bash-autocompletion] Check clang version in Bash
[Bash-autocompletion] Check clang version in Bash

Summary:
Add check if user's clang version supports --autocomplete or not.
If not, we just autocomplete files.

Reviewers: ruiu, v.g.vassilev, teemperor

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D34607

git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@306555 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang