Update dependencies from https://github.com/dotnet/winforms build 20190827.3 (#1730)

- Microsoft.Private.Winforms - 4.8.0-rc1.19427.3

eng/Version.Details.xml

 <?xml version="1.0" encoding="utf-8"?>
 <Dependencies>
   <ProductDependencies>
-    <Dependency Name="Microsoft.Private.Winforms" Version="4.8.0-rc1.19427.1">
+    <Dependency Name="Microsoft.Private.Winforms" Version="4.8.0-rc1.19427.3">
       <Uri>https://github.com/dotnet/winforms</Uri>
-      <Sha>c4375c2337aafbc77cdb399661845e94f618bcee</Sha>
+      <Sha>1792c81a53817480ceb5ddc9e34066a5c4089b98</Sha>
     </Dependency>
   </ProductDependencies>
   <ToolsetDependencies>

eng/Versions.props

@@ -8,7 +8,7 @@
   </PropertyGroup>
   <!-- NuGet Package Versions -->
   <PropertyGroup>
-    <MicrosoftPrivateWinformsVersion>4.8.0-rc1.19427.1</MicrosoftPrivateWinformsVersion>
+    <MicrosoftPrivateWinformsVersion>4.8.0-rc1.19427.3</MicrosoftPrivateWinformsVersion>
   </PropertyGroup>
   <!-- Packages that come from https://github.com/dotnet/coreclr -->
   <PropertyGroup>