Avoid duplicate class for mark compact

Renamed BitmapSetSlowPathVisitor to MCBitmapSetSlowPathVisitor for
the mark compact case.

Bug: 29413717

(cherry picked from commit d528f6819571ce5276cb71134044c55408a901a1)

Change-Id: Id5a7040c0c22a7a66309b8cbd7f874819852b10e
1 file changed