cmd/go: convert TestGoBuildARM to the script framework

Part of converting all tests to script framework to improve
test parallelism.

Updates #36320
Updates #17751

Change-Id: If1e591f28d6399a07b37ed7f4a1419bf7cd915eb
Reviewed-on: https://go-review.googlesource.com/c/go/+/214425
Reviewed-by: Jay Conrod <jayconrod@google.com>

src/cmd/go/go_test.go

@@ -2117,26 +2117,6 @@ func TestGoBuildGOPATHOrderBroken(t *testing.T) {
 	tg.run("install", "-x", "bar")
 }
 
-func TestGoBuildARM(t *testing.T) {
-	if testing.Short() {
-		t.Skip("skipping cross-compile in short mode")
-	}
-
-	tg := testgo(t)
-	defer tg.cleanup()
-
-	tg.makeTempdir()
-	tg.cd(tg.path("."))
-
-	tg.setenv("GOARCH", "arm")
-	tg.setenv("GOOS", "linux")
-	tg.setenv("GOARM", "5")
-	tg.tempFile("hello.go", `package main
-		func main() {}`)
-	tg.run("build", "hello.go")
-	tg.grepStderrNot("unable to find math.a", "did not build math.a correctly")
-}
-
 // For issue 14337.
 func TestParallelTest(t *testing.T) {
 	tooSlow(t)

src/cmd/go/testdata/script/build_arm.txt

@@ -0,0 +1,13 @@
+[short] skip 'skipping cross-compile in short mode'
+
+env GOARCH=arm
+env GOOS=linux
+env GOARM=5
+
+go build hello.go
+! stderr 'unable to find math.a'
+
+-- hello.go --
+package main
+
+func main() {}