src: remove reference to since-deleted dist -s flag

(Found while debugging release problems with go1.6beta1)

Updates #12002

Change-Id: Iec197a754205e7fd28be154f27f17f3315886364
Reviewed-on: https://go-review.googlesource.com/18011Reviewed-by: Chris Broadfoot <cbro@golang.org>

src/make.bash

@@ -44,8 +44,7 @@
 # This is used by cgo. Default is CXX, or, if that is not set, 
 # "g++" or "clang++".
 #
-# GO_DISTFLAGS: extra flags to provide to "dist bootstrap". Use "-s"
-# to build a statically linked toolchain.
+# GO_DISTFLAGS: extra flags to provide to "dist bootstrap".
 
 set -e
 if [ ! -f run.bash ]; then