Enable TestFdLeak on linux
Enable TestFdLeak on linux

it has been consistently passing at least the last 100 builds on the bot.

git-svn-id: 4c4cc70b1ef44ba2b7963015e681894188cea27e@246761 91177308-0d34-0410-b5e6-96231b3b80d8

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