message: README: update the CI links
  Several of the links were returning 404. Reading the job configuration
  [swift.org][0]. The listed jobs are
  | LLDB Incremental  |
  | |
  | macOS             |
  | Ubuntu 14.04      |
  | Ubuntu 16.04      |
  | Ubuntu 18.04      |
  [0]:
diff: || **Status** |
  |---|---|
  -|**macOS** |[![Build Status](https://ci.swift.org/job/oss-lldb-incremental-osx/badge/icon)](https://ci.swift.org/job/oss-lldb-incremental-osx)|
  +|**macOS** |[![Build Status](https://ci.swift.org/job/oss-lldb-incremental-osx-cmake/badge/icon)](https://ci.swift.org/job/oss-lldb-incremental-osx)|
  +|**Ubuntu 14.04** |[![Build Status](https://ci.swift.org/job/oss-lldb-incremental-linux-ubuntu-14_04/badge/icon)](https://ci.swift.org/job/oss-lldb-incremental-linux-ubuntu-14_04)|
  |**Ubuntu 16.04** |[![Build Status](https://ci.swift.org/job/oss-lldb-incremental-linux-ubuntu-16_04/badge/icon)](https://ci.swift.org/job/oss-lldb-incremental-linux-ubuntu-16_04)|
  -|**Ubuntu 16.10** |[![Build Status](https://ci.swift.org/job/oss-lldb-incremental-linux-ubuntu-16_10/badge/icon)](https://ci.swift.org/job/oss-lldb-incremental-linux-ubuntu-16_10)|
  +|**Ubuntu 18.04** |[![Build Status](https://ci.swift.org/job/oss-lldb-incremental-linux-ubuntu-18_04/badge/icon)](https://ci.swift.org/job/oss-lldb-incremental-linux-ubuntu-18_04)|
  **Welcome to the Swift Debugger and REPL!**
  