build: use go tool dist list

Change-Id: I9b79bd301d0b75ca1f16d4a05e3cb687a8428c14
Reviewed-on: https://go-review.googlesource.com/19884
Run-TryBot: Minux Ma <minux@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/buildall.bash

@@ -32,13 +32,13 @@ if [ "$pattern" = "" ]; then
     pattern=.
 fi
 
-# put linux, nacl first in the target list to get all the architectures up front.
-targets="$((ls runtime | sed -n 's/^rt0_\(.*\)_\(.*\)\.s/\1-\2/p'; echo linux-386-387 linux-arm-arm5) | sort | sed -e 's|linux-mips64x|linux-mips64 linux-mips64le|' | egrep -v android-arm | egrep "$pattern" | egrep 'linux|nacl')
-$(ls runtime | sed -n 's/^rt0_\(.*\)_\(.*\)\.s/\1-\2/p' | egrep -v 'android-arm|darwin-arm' | egrep "$pattern" | egrep -v 'linux|nacl')"
-
 ./make.bash || exit 1
 GOROOT="$(cd .. && pwd)"
 
+# put linux, nacl first in the target list to get all the architectures up front.
+targets="$((../bin/go tool dist list | sed -n 's/^\(.*\)\/\(.*\)/\1-\2/p'; echo linux-386-387 linux-arm-arm5) | sort | egrep -v android-arm | egrep "$pattern" | egrep 'linux|nacl')
+$(../bin/go tool dist list | sed -n 's/^\(.*\)\/\(.*\)/\1-\2/p' | egrep -v 'android-arm|darwin-arm' | egrep "$pattern" | egrep -v 'linux|nacl')"
+
 failed=false
 for target in $targets
 do