cmd/compile/internal/inline: ignore superfluous slicing

cmd/compile/internal/inline: ignore superfluous slicing

When slicing, ignore expressions which could be elided, as in slicing
starting at 0 or ending at len(v).

Fixes #75278

Change-Id: I9c18e29c3d4da9bef89bd25bb261d3cb60e66392
Reviewed-on: https://go-review.googlesource.com/c/go/+/701216
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Auto-Submit: Keith Randall <khr@golang.org>
Reviewed-by: Mark Freeman <markfreeman@google.com>