cmd/compile: enable indexed export format by default

Change-Id: Id018eeb79afbe2c695a583b3845cfbc1aab08388
Reviewed-on: https://go-review.googlesource.com/106797
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

src/cmd/compile/internal/gc/main.go

@@ -244,7 +244,7 @@ func Main(archInit func(*Arch)) {
 	flag.StringVar(&blockprofile, "blockprofile", "", "write block profile to `file`")
 	flag.StringVar(&mutexprofile, "mutexprofile", "", "write mutex profile to `file`")
 	flag.StringVar(&benchfile, "bench", "", "append benchmark times to `file`")
-	flag.BoolVar(&flagiexport, "iexport", false, "export indexed package data")
+	flag.BoolVar(&flagiexport, "iexport", true, "export indexed package data")
 	objabi.Flagparse(usage)
 
 	// Record flags that affect the build result. (And don't