gm self-test: use a pathologically simple test case instead of dashing2

gm/tests/outputs/aaclip-readback/output-expected/json-summary.txt

Index: gm/tests/outputs/aaclip-readback/output-expected/json-summary.txt
===================================================================
--- gm/tests/outputs/aaclip-readback/output-expected/json-summary.txt	(revision 7909)
+++ gm/tests/outputs/aaclip-readback/output-expected/json-summary.txt	(working copy)
@@ -5,20 +5,20 @@
       "no-comparison" : null,
       "succeeded" : {
          "simpleaaclip_path_565" : {
-            "checksum" : FAKE
+            "checksum" : 8375148850964385904

[epoger, 2013/03/01 12:04:40]

Now that we use this (hopefully!) cross-platform self-test, we can leave real
checksums in the comparison JSON files.  Makes life easier...

          },
          "simpleaaclip_path_8888" : {
-            "checksum" : FAKE
+            "checksum" : 4719056555285640269
          }
       }
    },
    "expected-results" : {
       "simpleaaclip_path_565" : {
-         "checksums" : [ FAKE ],
+         "checksums" : [ 8375148850964385904 ],
          "ignore-failure" : false
       },
       "simpleaaclip_path_8888" : {
-         "checksums" : [ FAKE ],
+         "checksums" : [ 4719056555285640269 ],
          "ignore-failure" : false
       }
    }