cmd/go/internal/modload: use lockedfile.Read for the initial read of the go.mod file

Updates #34634
Fixes #35425

Change-Id: I878a8d229b33dcde9e7d4dfd82ddf9815d38a465
Reviewed-on: https://go-review.googlesource.com/c/go/+/206142
Run-TryBot: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/go/internal/modload/init.go

@@ -28,7 +28,6 @@ import (
 	"cmd/go/internal/modfetch"
 	"cmd/go/internal/modfetch/codehost"
 	"cmd/go/internal/mvs"
-	"cmd/go/internal/renameio"
 	"cmd/go/internal/search"
 
 	"golang.org/x/mod/modfile"
@@ -398,7 +397,7 @@ func InitMod() {
 	}
 
 	gomod := ModFilePath()
-	data, err := renameio.ReadFile(gomod)
+	data, err := lockedfile.Read(gomod)
 	if err != nil {
 		base.Fatalf("go: %v", err)
 	}