Fix to compute_changes (touches could sometimes override data changes)
Merge branch 'next' of github.com:rethinkdb/rethinkdb into next
Use the same compiler to build the dependencies

Closes issue #2057
Review 1291 by @Tryneus
Change call to map::erase to work on GCC 4.4

Closes #2064
Review 1293 by @mlucy
Merge branch 'next' of github.com:rethinkdb/rethinkdb into next
Merge branch 'next' into sam_thicklist