i#689 part 3: avoid lock + hashtable lookup by caching retaddrs + cache last 8 retaddrs
i#689 part 3: avoid lock + hashtable lookup by caching retaddrs
+ cache last 8 retaddrs

SVN-Revision: 1273

sigma-random/dynamorio,AmesianX/dynamorio,bl4ckic3/dynamorio,code4bones/dynamorio,code4bones/dynamorio,sigma-random/dynamorio,daksunt/dynamorio,code4bones/dynamorio,daksunt/dynamorio,AmesianX/dynamorio,daksunt/dynamorio,code4bones/dynamorio,sigma-random/dynamorio,AmesianX/dynamorio,bl4ckic3/dynamorio,AmesianX/dynamorio,daksunt/dynamorio,code4bones/dynamorio,sigma-random/dynamorio,daksunt/dynamorio,bl4ckic3/dynamorio,bl4ckic3/dynamorio,sigma-random/dynamorio,AmesianX/dynamorio,bl4ckic3/dynamorio