runtime: remove scase.releasetime field

This is the gofrontend version of
Original CL description:

    selectgo will report at most one block event, so there's no need to
    keep a releasetime for every select case. It suffices to simply track
    the releasetime of the case responsible for the wakeup.

    Updates golang/go#40410.

This is being brought over to gofrontend as a step toward upgrading to

Change-Id: I60688303cdae72f89cfa9777402933ecee2503f7
Trust: Ian Lance Taylor <>
Reviewed-by: Than McIntosh <>
2 files changed