ola: Bump to 0.9.4

The protoc stuff changed a bit since 0.9.3. When 0.9.4 was released,
support for cross-compiling was broken because of it. A patch was merged
upstream shortly after that fixes the problem, so I included it here.
When the next version is released, the patch should not be necessary
anymore.

[Peter: actually change _VERSION]
Signed-off-by: Simon Marchi <simon.marchi@polymtl.ca>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>