cmd/dist: run testshared on linux/ppc64le

Change-Id: I4d079d29408e5344701056c88882cfd3b3857478
Reviewed-on: https://go-review.googlesource.com/15973Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Michael Hudson-Doyle <michael.hudson@canonical.com>

src/cmd/dist/test.go

@@ -587,7 +587,7 @@ func (t *tester) supportedBuildmode(mode string) bool {
 		return false
 	case "shared":
 		switch pair {
-		case "linux-amd64", "linux-arm":
+		case "linux-amd64", "linux-arm", "linux-ppc64le":
 			return true
 		}
 		return false