bpo-29505: Add more fuzzing for re.compile, re.load and csv.reader (GH-14255)

Add more fuzz testing for re.compile, re.load and csv.reader
diff --git a/Lib/test/test_xxtestfuzz.py b/Lib/test/test_xxtestfuzz.py
index 532f5fe..15924aa 100644
--- a/Lib/test/test_xxtestfuzz.py
+++ b/Lib/test/test_xxtestfuzz.py
@@ -16,6 +16,8 @@
         _xxtestfuzz.run(b" ")
         _xxtestfuzz.run(b"x")
         _xxtestfuzz.run(b"1")
+        _xxtestfuzz.run(b"AAAAAAA")
+        _xxtestfuzz.run(b"AAAAAA\0")
 
 
 if __name__ == "__main__":