crash-reporter: fix bug where we were sending "undefined" as all stack signatures

Also, move the logic for picking which extra parameters to send up above where mock sending ends so UserCrash detects this regression in the future.  And merge unknown and undefined special strings into one to avoid confusion.

Change-Id: Ic55a0c5b473a0cef39eac2c1250d1607deffe050

TEST=User/KernelCrash and CrashSender

Review URL:
1 file changed
tree: e54592ab8a9d73a50cd8b21be2e41868ece48f1a
  1. crash_reporter/