Remove reset_ecs and execution_control_state::reset

Remove reset_ecs and execution_control_state::reset

I noticed that execution_control_state has a 'reset' method, and
there's also a 'reset_ecs' function that calls it.  This patch cleans
this area up a little by adding a parameter to the constructor and (a
change Simon suggested) removing the reset method.  Some extraneous
variables are also removed, like:

-      struct execution_control_state ecss;
-      struct execution_control_state *ecs = &ecss;

Here 'ecs' is never changed, so this patch removes it entirely in
favor of just using the object everywhere.

Regression tested on x86-64 Fedora 34.

Approved-By: Simon Marchi <simon.marchi@efficios.com>