Zephyr SDK 0.13.0-rc4

(Changes since 0.13.0-rc3)

• newlib:

  • Fix nano.spec file to pull in nano libraries.
  • Set -mthumb-interwork for nano newlib builds to workaround
    at crosstool issue.

• general:

  • CI/go.sh changes to make building MacOS and CI building
    easier.