Clear plaintext when AesCcm authentication fails

[krwq]

Fixes: https://github.com/dotnet/corefx/issues/32710

Seems whatever version of OpenSsl ships on Arm64 it does not clear plaintext when authentication fails.

Adding it on all platforms - since it's a failing path the perf is irrelevant

[krwq]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 4 pipeline(s).

[krwq]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 4 pipeline(s).

[krwq]

Sanity started manual run just in case since the CI skipped running tests on arm64 on this iteration:
https://dev.azure.com/dnceng/public/_build/results?buildId=239397

[bartonjs]

Debian.9.Arm32.Open-arm:

===========================================================================================================
/root/helix/work/workitem /root/helix/work/workitem
  Discovering: System.Data.Common.Tests (method display = ClassAndMethod, method display options = None)
  Discovered:  System.Data.Common.Tests (found 1785 of 1787 test cases)
  Starting:    System.Data.Common.Tests (parallel test collections = on, max threads = 4)
./RunTests.sh: line 164:    16 Aborted                 (core dumped) "$RUNTIME_PATH/dotnet" xunit.console.dll System.Data.Common.Tests.dll -xml testResults.xml -nologo -nocolor -notrait category=nonnetcoreapptests -notrait category=nonlinuxtests -notrait category=IgnoreForCI -notrait category=OuterLoop -notrait category=failing $RSP_FILE
/root/helix/work/workitem
----- end Wed Jun 26 11:44:26 UTC 2019 ----- exit code 134 ----------------------------------------------------------
exit code 134 means SIGABRT Abort. Managed or native assert, or runtime check such as heap corruption, caused call to abort(). Core dumped.
Looking around for any Linux dump...
... found no dump in /root/helix/work/workitem

Debian.9.Arm32.Open-arm:

===========================================================================================================
/root/helix/work/workitem /root/helix/work/workitem
  Discovering: System.Runtime.Tests (method display = ClassAndMethod, method display options = None)
  Discovered:  System.Runtime.Tests (found 5327 of 5368 test cases)
  Starting:    System.Runtime.Tests (parallel test collections = on, max threads = 4)
./RunTests.sh: line 164:    16 Aborted                 (core dumped) "$RUNTIME_PATH/dotnet" xunit.console.dll System.Runtime.Tests.dll -xml testResults.xml -nologo -nocolor -notrait category=nonnetcoreapptests -notrait category=nonlinuxtests -notrait category=IgnoreForCI -notrait category=OuterLoop -notrait category=failing $RSP_FILE
/root/helix/work/workitem
----- end Wed Jun 26 11:47:49 UTC 2019 ----- exit code 134 ----------------------------------------------------------
exit code 134 means SIGABRT Abort. Managed or native assert, or runtime check such as heap corruption, caused call to abort(). Core dumped.

And it also hit #38444.

None of these really seem related to this change; and all of the System.Security.Cryptography tests passed on all configs. So it seems mergable.