Switch threading mode for tests on Windows when there are lots of cores. This prevents a "too many files" error.
Switch threading mode for tests on Windows when there are lots of cores.
This prevents a "too many files" error.

Differential Revision: http://reviews.llvm.org/D13555

git-svn-id: 4c4cc70b1ef44ba2b7963015e681894188cea27e@250044 91177308-0d34-0410-b5e6-96231b3b80d8

apple/swift-lldb,apple/swift-lldb,llvm-mirror/lldb,llvm-mirror/lldb,llvm-mirror/lldb,llvm-mirror/lldb,apple/swift-lldb,llvm-mirror/lldb,apple/swift-lldb,apple/swift-lldb,apple/swift-lldb