detect access boundary of the redzone in pattern mode

_From [zhao...@google.com](https://code.google.com/u/106321947286816917100/) on March 06, 2012 10:36:51_

split from issue #775 .
A memory reference might access multi-byte that partially in addressable region and partially in the redzone, which makes it difficult to detect in pattern mode.

_Original issue: http://code.google.com/p/drmemory/issues/detail?id=811_