[nomerge] SI-9030 don't call private BoxesRunTime.equalsNumChar

When comparing a Number and a Character, the would emit a call to the
private method. For binary compatibility, this method remains private
in 2.11, so we just use equalsNumObject instead.
Merge pull request #4196 from lrytz/t9030-2.11

[nomerge] SI-9030 don't call private BoxesRunTime.equalsNumChar