oeqa qemurunner.py: try to avoid reading one character at a time

Read from serial console with a small delay to bundle data to e.g.
full lines. Reading one character at a time is not needed and causes
busy looping.

(From OE-Core rev: e91a09702680b713293bcfcc851b27a73e884a8b)

Signed-off-by: Mikko Rapeli <mikko.rapeli@linaro.org>
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
(cherry picked from commit 0049f6757f6f956fb4cc77b3df6a672c20b53cf4)
Signed-off-by: Steve Sakoman <steve@sakoman.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/lib/oeqa/utils/qemurunner.py

@@ -647,6 +647,8 @@ class QemuRunner:
             except InterruptedError:
                 continue
             if sread:
+                # try to avoid reading single character at a time
+                time.sleep(0.1)
                 answer = self.server_socket.recv(1024)
                 if answer:
                     data += answer.decode('utf-8')