Portable Python script across Python version
Portable Python script across Python version

Use higher-level and more compatible threading module to start a new thread.

Differential Revision: https://reviews.llvm.org/D55259

git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@349008 91177308-0d34-0410-b5e6-96231b3b80d8

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