on-stack check on unaddr very slow on linux

_From [bruen...@google.com](https://code.google.com/u/109494838902877177630/) on January 19, 2011 10:45:29_

for apps with a lot of unaddressable errors, the allocation_size() call that queries the maps file (via dr_query_memory()) on linux is very slow. drmem could try to cache all the stack regions instead.

_Original issue: http://code.google.com/p/drmemory/issues/detail?id=272_