cmd/go: cache results of exec.LookPath
This CL package exec.LookPath to internal/cfg.LookPath and adds cache.
BenchmarkLookPath-4
24149096 50.48 ns/op 0 B/op 0 allocs/op
Fixes #36768
Change-Id: I199a780d1eab9bd5397bb3759bb42191fff716e9
Change-Id: I199a780d1eab9bd5397bb3759bb42191fff716e9
GitHub-Last-Rev:
d67aa826f431affe829c23d1fdf2241fbb611303
GitHub-Pull-Request: golang/go#61464
Reviewed-on: https://go-review.googlesource.com/c/go/+/511458
Run-TryBot: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>
Auto-Submit: Bryan Mills <bcmills@google.com>
Reviewed-by: Heschi Kreinick <heschi@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>