[build]: Build on Arch Linux with python 2.7-3.8

This change allow builds to succeed on Arch Linux with python 2.7, 3.7.4
and 3.8. Otherwise it fails with python 3.7.4 and 3.8.

- Add `universal_newlines=True` so subprocess stdout is opened in text mode.

Test: No added tests as there are no behavioral changes.
Change-Id: I0e156fe42a4fe13b14cdd4b97e8c081a727cf9b2
1 file changed