[build] set $(GitCommits) to 0

Might fix:

    /Users/builder/.nuget/packages/gitinfo/2.1.2/build/GitInfo.targets(876,4):
    error MSB4186: Invalid static method invocation syntax:
    "[MSBuild]::Add('$(GitBaseVersionPatch)', '$(GitCommits)')". Method '[MSBuild]::Add' not found. Static method invocation should be of the form: $([FullTypeName]::Method()), e.g. $([System.IO.Path]::Combine(`a`, `b`)).
    Check that all parameters are defined, are of the correct type, and are specified in the right order.
    [/Users/builder/azdo/_work/14/s/xamarin-android/external/xamarin-android-tools/src/Microsoft.Android.Build.BaseTasks/Microsoft.Android.Build.BaseTasks.csproj::TargetFramework=net6.0]

Directory.Build.props

@@ -26,6 +26,8 @@
     <SuppressNETCoreSdkPreviewMessage>true</SuppressNETCoreSdkPreviewMessage>
     <!-- Disables the transitive restore of packages like Microsoft.AspNetCore.App.Ref, Microsoft.WindowsDesktop.App.Ref -->
     <DisableTransitiveFrameworkReferenceDownloads>true</DisableTransitiveFrameworkReferenceDownloads>
+    <!-- HACK: fixes GitInfo in submodules -->
+    <GitCommits>0</GitCommits>
   </PropertyGroup>
 
   <PropertyGroup>