Added comments referencing multiple CVEs in tests and production code.

This commit adds comments referencing multiple CVEs both in production and test code.
CVEs covered in this commit:

CVE-2010-5137
CVE-2010-5139
CVE-2010-5141
CVE-2012-1909
CVE-2012-2459
CVE-2012-3789
CVE-2018-17144

test/functional/feature_block.py

@@ -787,7 +787,7 @@ class FullBlockTest(BitcoinTestFramework):
         #
         # Blocks are not allowed to contain a transaction whose id matches that of an earlier,
         # not-fully-spent transaction in the same chain. To test, make identical coinbases;
-        # the second one should be rejected.
+        # the second one should be rejected. See also CVE-2012-1909.
         #
         self.log.info("Reject a block with a transaction with a duplicate hash of a previous transaction (BIP30)")
         self.move_tip(60)