Fix unicode display in parameters

When parameters contain unicode, stack-show will display unicode
as '\u2665'. It's not easy to read by human.
This change will change '\u2665' to readable unicode char '♥' when
display to users.

Change-Id: I00a74943138b292b71f848966ee64a658be64bc2
Partial-Bug: #1330370
Merge "Fix unicode display in parameters"