cmd/dist: drop ppc64le from testcshared

I'm glad my CL fixed the library use case inside Google.
It fixes neither of the two tests here.

Change-Id: Ica91722dced8955a0a8ba3aad3d288816b46564e
Reviewed-on: https://go-review.googlesource.com/23482
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>

src/cmd/dist/test.go

@@ -688,8 +688,7 @@ func (t *tester) supportedBuildmode(mode string) bool {
 		switch pair {
 		case "linux-386", "linux-amd64", "linux-arm", "linux-arm64",
 			"darwin-amd64", "darwin-386",
-			"android-arm", "android-arm64", "android-386",
-			"linux-ppc64le":
+			"android-arm", "android-arm64", "android-386":
 			return true
 		}
 		return false