tests/attrtest: move decl to non-test file

Solves the asmdecl error:

  [amd64] AttrTest: function AttrTest missing Go declaration

Updates #24

tests/textflag/attrtest_test.go

@@ -2,12 +2,8 @@ package textflag
 
 import "testing"
 
-//go:generate go run make_attrtest.go -output zattrtest.s -seed 42 -num 256
-
-func AttrTest() bool
-
 func TestAttributes(t *testing.T) {
-	if !AttrTest() {
+	if !attrtest() {
 		t.Fail()
 	}
 }