Update boringssl to allow compilation in MacOS XCode 14.3
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For the most up to date status, view the checks section at the bottom of the pull request. This has not been merged in the 2.12.1 release. Not sure why, but it should.  It did not land on master and was not cherrypicked. Too late now for 2.12.x series since @learning-to-play and team decided to only patch the last release, so now only 2.13 will get patches. @feranick Please see if [TF patching guidelines](https://github.com/tensorflow/tensorflow#patching-guidelines) can provide a solution for your case. I have a solution to my case. I found it, reported here, created a pull request, that was reviewed and accepted for release. But then it was neither landed on master nor cherrypicked. As a result, the problem remains for whoever is trying to compile 2.12.x on MacOS. Patching guidelines are just that, a guideline for a specific patch. Since my patch has not been cherrypicked, suggesting the use of the patching guidelines becomes pointless and irrelevant.

So this (resolved) bug report is the only place where one can find a solution, and manually apply the patch. I would expect more, at the very least list it in the "known issues" so there is some guidance. Again, I am fine as I found a solution myself, but frankly going to the trouble to push it upstream through the official channels only to find that it's considered irrelevant, doesn't really inspire any future effort on my part to contribute patches. 

Besides 2.13.0 is out now and does not suffer from this. 

Thank you for your help.
Current version of boringssl pulled for TF 2.12.x does not compile with TF using XCode 14.3 due to an unused variable and an aggressive compiler flag (-Werror,-Wunused-but-set-variable) This patch adds links to an updated version of boringssl (used for TF Master), that fixes the issue. This fixes TF issue #60191