X509Chain tests failing on macOS 10.14

[bartonjs]

It looks like 10.14 has started reporting a GrayListedLeaf code, which is tripping our "I don't know how to handle this code" code.

It needs to be added to the ignore-this list, with the already present GrayListedKey.

Currently affecting dotnet/corefx#42873, and rolling builds in dotnet/runtime/master.

[jaredpar]

This is presently blocking our CI builds

Builds

Build	Pull Request	Test Failure Count
#536515	Rolling	2
#536676	Rolling	2
#536970	Rolling	2
#537092	Rolling	2
#537160	Rolling	2
#537205	Rolling	2
#537477	Rolling	2
#537629	Rolling	2
#537845	Rolling	2
#538096	Rolling	2

Configurations

• netcoreapp5.0-OSX-Release-x64-CoreCLR_release-OSX.1014.Amd64.Open
• netcoreapp5.0-OSX-Release-x64-Mono_release-OSX.1014.Amd64.Open

Helix Logs

Build	Pull Request	Console	Core	Test Results
#536515	Rolling	console.167a61dc.log		testResults.xml
#536515	Rolling	console.8ed056e1.log		testResults.xml
#536676	Rolling	console.625c961a.log		testResults.xml
#536676	Rolling	console.b0f96254.log		testResults.xml
#536970	Rolling	console.7eca51ef.log		testResults.xml
#536970	Rolling	console.a17cc70d.log		testResults.xml
#537092	Rolling	console.3bcc79f9.log		testResults.xml
#537092	Rolling	console.57a59cff.log		testResults.xml
#537160	Rolling	console.19cc83c5.log		testResults.xml
#537160	Rolling	console.68f93407.log		testResults.xml
#537205	Rolling	console.aa77eb90.log		testResults.xml
#537205	Rolling	console.4342a2ac.log		testResults.xml
#537477	Rolling	console.a6470430.log		testResults.xml
#537477	Rolling	console.2cac7143.log		testResults.xml
#537629	Rolling	console.d8a81bd6.log		testResults.xml
#537629	Rolling	console.8f7518e6.log		testResults.xml
#537845	Rolling	console.624a818f.log		testResults.xml
#537845	Rolling	console.d9b97643.log		testResults.xml
#538096	Rolling	console.08526ae5.log		testResults.xml
#538096	Rolling	console.6762b273.log		testResults.xml