strconv: use switch for '+'/'-' prefix handling
Follow the approach used in strconv's readFloat, decimal.set, and Atoi,
where leading '+' and '-' are handled using a switch for clarity and
consistency.
Change-Id: I41eff34ce90b5ac43fcdbc0bb88910d6d5fb4d39
GitHub-Last-Rev:
0c9d2efb5a828515fa00afdba8c436aa31fb0e53
GitHub-Pull-Request: golang/go#73185
Reviewed-on: https://go-review.googlesource.com/c/go/+/663257
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Auto-Submit: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>