Guard against the most recent write operation instead. Accumulate read
bindings to a) not issue unnecessary barriers when a resource has
multiple read-only usages, and b) synchronize with all previous read
bindings when writing.

This is motivated by an issue where a program using a single buffer to
store both indices and vertex attributes causes superfluous barriers on
each draw call.
Signed-off-by: Jan Sikorski <jsikorski@codeweavers.com>
Signed-off-by: Henri Verbeet <hverbeet@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>