make the example-test private file's work be behind a thunk (so more drdr friendly)

collects/tests/drracket/example-tool.rkt

@@ -29,4 +29,6 @@
                 (cons
                  new-collection-root
                  (current-library-collection-paths))])
-  (namespace-require 'tests/drracket/private/run-example-tool))
+  (namespace-require 'tests/drracket/private/run-example-tool)
+  (eval '(go)))
+

collects/tests/drracket/private/run-example-tool.rkt

@@ -20,6 +20,10 @@
          framework/test
          mrlib/switchable-button)
 
+(provide go)
+
+(define (go)
+  
   (define init-options@
     (unit (import setup-option^)
           (export)
@@ -76,5 +80,4 @@
        (fprintf (current-error-port) 
                 "example-tool.rkt: test failed;\nexpected ~s\n but got ~s"
                 expected
-              content))))
-
+                content)))))