Some variables were either unused or only used in certain contexts,
like debug or tracing, so these were either removed (when unused)
or moved to the right scope (when used conditionally).
Also fixed a string format warning and a missing case warning.

Change-Id: I2d130faa992b5dc06fb332d7404a8aebc7c121ef
Reviewed-on: https://swiftshader-review.googlesource.com/5462Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>