handle symbols for interception pointing into unmapped holes in modules

_From [bruen...@google.com](https://code.google.com/u/109494838902877177630/) on January 03, 2012 17:41:02_

split from issue #730 this is very unlikely and would require a malicious or buggy module w/ invalid debug info. it would have to be on linux.

filing just to have a record of it. see comment 2 in issue #730 .

_Original issue: http://code.google.com/p/drmemory/issues/detail?id=731_