classes/lib: Update to use python3 command pipeline decoding

In python3, strings are unicode by default. We need to encode/decode
from command pipelines and other places where we interface with the
real world using the correct locales. This patch updates various
call sites to use the correct encoding/decodings.

(From OE-Core rev: bb4685af1bffe17b3aa92a6d21398f38a44ea874)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/lib/oeqa/utils/sshcontrol.py

@@ -58,6 +58,7 @@ class SSHProcess(object):
                         self.process.stdout.close()
                         eof = True
                     else:
+                        data = data.decode("utf-8")
                         output += data
                         self.log(data)
                         endtime = time.time() + timeout