[libclang] For c-index-test disable caching of code completion results if the CINDEXTEST_COMPLETION_NO_CACHING environment variable is present.
[libclang] For c-index-test disable caching of code completion results if
the CINDEXTEST_COMPLETION_NO_CACHING environment variable is present.

git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@143604 91177308-0d34-0410-b5e6-96231b3b80d8

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