Initialize EO::current_frame_idx_m in constructor

Initialize ExecutionObject::current_frame_idx_m array to 0 in the
ExecutionObject constructor to prevent out of range entries when
recording trace data.

In a pipelined processing loop, the application executes
ExecutionObject::ProcessFrameWait() on the first frame before it calls
ExecutionObject::ProcessFrameStartAsync. The side effect is that the
current_frame_idx_m is not initialized. This can result in negative
frame indices when writing trace data using ReportTrace or UpdateTrace
leading to memory errors.

Setting ExecutionObject::current_frame_idx_m to 0 in the constructor
avoids this scenario.

(MCT-1085)