performance fix for i#260 change: + switch from hashtable_remove_range to a loop that does lookup for every   byte in bb, which is a noticeable perf win b/c xl8_sharing_table gets   quite large and walking on every fragment delete is expensive
performance fix for i#260 change:
+ switch from hashtable_remove_range to a loop that does lookup for every
  byte in bb, which is a noticeable perf win b/c xl8_sharing_table gets
  quite large and walking on every fragment delete is expensive

git-svn-id: fe3cd4388a6e5a968b09397a3d721fe124e8117a@480 5b54908e-ead4-fc18-b48a-0285e6dbc711

rnk/drmemory,rnk/drmemory,rnk/drmemory,rnk/drmemory