* In the conflicting-event mechanism, also record the size and

* In the conflicting-event mechanism, also record the size and
  read-or-writeness of each access, so that these can be displayed in
  error messages.

* Use recorded read-or-writeness info to avoid producing error
  messages that claim claim two reads race against each other -- this
  is clearly silly.  For each pair of racing accesses now reported, at
  least one of them will (should!) always now be a write, and (as
  previously ensured) they will be from different threads.

* Lookups in the conflicting-access map is expensive, so don't do that
  as soon as a race is detected.  Instead wait until the update_extra
  method is called.

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@8809