[master] Update dependencies from dotnet/coreclr (dotnet/corefx#42121)
* Update dependencies from https://github.com/dotnet/coreclr build
20191025.1
- Microsoft.NET.Sdk.IL - 5.0.0-alpha1.19525.1
- Microsoft.NETCore.ILAsm - 5.0.0-alpha1.19525.1
- Microsoft.NETCore.Runtime.CoreCLR - 5.0.0-alpha1.19525.1
* remove Stopwatch.*.cs from System.Runtime.Extensions build
* Disable tests against CoreCLR bug
Commit migrated from https://github.com/dotnet/corefx/commit/
8245ee1e8f6063ccc7a3a60cafe821d29e85b02f