i#1673 port ext to ARM: fix drwrap decorated PC bug
i#1673 port ext to ARM: fix drwrap decorated PC bug

Fixes a bug where the plain PC (i.e., minus the LSB marker for Thumb mode)
is used to redirect on a flush when the retaddr already exists, leading to
crashes when the target is interpreted in the wrong mode.

Review-URL: https://codereview.appspot.com/284310043

AmesianX/dynamorio,AmesianX/dynamorio,AmesianX/dynamorio,AmesianX/dynamorio,AmesianX/dynamorio