i#4607: Fix null pointer dereference in drwrap (#4709)
i#4607: Fix null pointer dereference in drwrap (#4709)

drwrap_ensure_postcall may not return. Thus, we should decrement
wrap_level, so, it won't be incremented again in drwrap_in_callee. We
reproduce the behavior prior to 9bb0354 commit which introduced
this regression.

Fixes #4607
Co-authored-by: Derek Bruening <9b9d6e0c3aa3b325e2741391232280bb0c64f6cc@google.com>
AmesianX/dynamorio,AmesianX/dynamorio,AmesianX/dynamorio,AmesianX/dynamorio,AmesianX/dynamorio