make run the default action of a test in tester

tests/modules/t8665.nim

@@ -1 +1,5 @@
+discard """
+  action: compile
+"""
+
 import treorder

tests/modules/texport2.nim

@@ -1,9 +1,16 @@
+discard """
+output: '''
+abc
+xyz
+B.foo
+'''
+"""
+
 # bug #1595, #1612
 
 import mexport2a
 
 proc main() =
-  echo "Import Test, two lines should follow. One with abc and one with xyz."
   printAbc()
   printXyz()