cmd/dist: enable plugin test on Linux/ARM64

The test was skipped because with the old gold linker on the
builder it fails with an internal error in gold. The builders now
have gold 2.31 and the test passes. Enable it.

Fixes #17138.

Change-Id: Ia0054030dd12f1d003c7420bf7ed8b112715baa9
Reviewed-on: https://go-review.googlesource.com/c/go/+/369814
Trust: Cherry Mui <[email protected]>
Run-TryBot: Cherry Mui <[email protected]>
Reviewed-by: Than McIntosh <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>

Author: cherrymui

src/cmd/dist/test.go

@@ -1043,10 +1043,8 @@ func (t *tester) supportedBuildmode(mode string) bool {
 		}
 		return false
 	case "plugin":
-		// linux-arm64 is missing because it causes the external linker
-		// to crash, see https://golang.org/issue/17138
 		switch pair {
-		case "linux-386", "linux-amd64", "linux-arm", "linux-s390x", "linux-ppc64le":
+		case "linux-386", "linux-amd64", "linux-arm", "linux-arm64", "linux-s390x", "linux-ppc64le":
 			return true
 		case "darwin-amd64", "darwin-arm64":
 			return true