Exclude ancm.mof from code signing

This file is not signable. The sign tool treats .mof as a potential signing candidate by default, even though most .mof files are not signable.

Author: Nate McMaster

build/CodeSign.props

@@ -71,6 +71,9 @@
       <FilesToSign Include="aspnetcorev2_inprocess.dll"                                     Certificate="$(AssemblySigningCertName)" Container="Microsoft.AspNetCore.App" />
       <FilesToSign Include="aspnetcorev2_outofprocess.dll"                                  Certificate="$(AssemblySigningCertName)" Container="Microsoft.AspNetCore.App" />
 
+      <!-- This is a text file which doesn't need to be code signed, even though some .mof files can be signed. -->
+      <FilesToExcludeFromSigning Include="ancm.mof" />
+
     <!-- These files came from partner teams. They have to be re-signed because we crossgen them and redistributable them in our installers. -->
 
       <!-- Microsoft.AspNetCore.All -->