Xcode 4.3 compatibility checkin

The update compiler in Xcode 4.3 (and 4.4) requires lookups into dependant
bases of class templates to be qualified. This checkin fixes the issues
raised by the compiler by implementing the this-> recommendation from
the llvm page at http://clang.llvm.org/compatibility.html#dep_lookup_bases



Signed-off-by: Al Sutton <al@funkyandroid.com>