runtime: ignore TestCgoPprofPIE test failures on Alpine (take 2)

s/arm64/amd64/ in previous typo CL 41628

Updates #19938
Updates #18243

Change-Id: I282244ee3c94535f229a87b6246382385ff64428
Reviewed-on: https://go-review.googlesource.com/41675Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/runtime/crash_cgo_test.go

@@ -282,7 +282,7 @@ func testCgoPprof(t *testing.T, buildArg, runArg string) {
 
 	got, err := testEnv(exec.Command(exe, runArg)).CombinedOutput()
 	if err != nil {
-		if testenv.Builder() == "linux-arm64-alpine" {
+		if testenv.Builder() == "linux-amd64-alpine" {
 			// See Issue 18243 and Issue 19938.
 			t.Skipf("Skipping failing test on Alpine (golang.org/issue/18243). Ignoring error: %v", err)
 		}