[foozzie] Don't use utf-8 encoding for console output.

BUG=chromium:673246,chromium:688307
NOTRY=true
R=tandrii@chromium.org
TBR=mstarzinger@chromium.org

Change-Id: I269032497cf574cf5180762e37b0fee1002a6c76
Reviewed-on: https://chromium-review.googlesource.com/437244Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Andrii Shyshkalov <tandrii@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#42931}

tools/foozzie/v8_foozzie.py

@@ -270,10 +270,12 @@ def main():
         second_config_label=second_config_label,
         first_config_flags=' '.join(first_config_flags),
         second_config_flags=' '.join(second_config_flags),
-        first_config_output=first_config_output.stdout,
-        second_config_output=second_config_output.stdout,
+        first_config_output=
+            first_config_output.stdout.decode('ascii', 'replace'),
+        second_config_output=
+            second_config_output.stdout.decode('ascii', 'replace'),
         source=source,
-        difference=difference,
+        difference=difference.decode('ascii', 'replace'),
     )
     return RETURN_FAIL