Force gdb to not print entry values.

All of a sudden gdb decided to start printing them, which messed up the
breakpoint test. It would only print them in the test, not if I manually
ran the same commands. I'm sure it's my fault somehow, but this should
keep things consistent in the future.

tests/testlib.py

@@ -71,6 +71,8 @@ class Gdb(object):
         self.wait()
         self.command("set width 0")
         self.command("set height 0")
+        # Force consistency.
+        self.command("set print entry-values no")
 
     def wait(self):
         """Wait for prompt."""