Restore missing API.

src/Compilers/Core/Portable/PublicAPI.Shipped.txt

@@ -389,6 +389,7 @@ Microsoft.CodeAnalysis.CommandLineArguments.EmitPdb.get -> bool
 Microsoft.CodeAnalysis.CommandLineArguments.EmitPdbFile.get -> bool
 Microsoft.CodeAnalysis.CommandLineArguments.Encoding.get -> System.Text.Encoding
 Microsoft.CodeAnalysis.CommandLineArguments.ErrorLogOptions.get -> Microsoft.CodeAnalysis.ErrorLogOptions
+Microsoft.CodeAnalysis.CommandLineArguments.ErrorLogPath.get -> string
 Microsoft.CodeAnalysis.CommandLineArguments.Errors.get -> System.Collections.Immutable.ImmutableArray<Microsoft.CodeAnalysis.Diagnostic>
 Microsoft.CodeAnalysis.CommandLineArguments.GetOutputFilePath(string outputFileName) -> string
 Microsoft.CodeAnalysis.CommandLineArguments.GetPdbFilePath(string outputFileName) -> string