title: iText7 with Android in Xamarin Compile Issue
body: <p>I have a project which uses a NuGet package called "iText" library. It has a dependency on the System.Runtime.Loader package. When I try to build the project, I got the exception copied below, because it tries to load a placeholder assembly with the name ".". Works fine for UWP and iOS.</p>
  
  <p>The problem occurs on both Visual Studio 2017 and Visual Studio for Mac. Both with the latest versions, with the latest Xamarin framework versions too.</p>
  
  <p>Also, if I remove that file from the referred folder, and place the System.Runtime.Loader.dll from the netstandard1.5 folder, and set the linking to "None", it works fine.</p>
  
  <h2>Exception:</h2>
  
  <blockquote>
    <p>/Library/Frameworks/Mono.framework/External/xbuild/Xamarin/Android/Xamarin.Android.Common.targets(2,2): Error: Exception while loading assemblies: Java.Interop.Tools.Diagnostics.XamarinAndroidException: error XA0009: Error while loading assembly: /Users/xxxx/.nuget/packages/system.runtime.loader/4.3.0/lib/MonoAndroid10/. ---> System.BadImageFormatException: Format of the executable (.exe) or library (.dll) is invalid. at Mono.Cecil.PE.ImageReader.ReadImage () [0x000fc] in /Users/builder/data/lanes/6090/86d33f45/source/monodroid/external/xamarin-android/external/mono/external/cecil/Mono.Cecil.PE/ImageReader.cs:94 at Mono.Cecil.PE.ImageReader.ReadImage (Mono.Disposable<code>1[T] stream, System.String file_name) [0x0000a] in /Users/builder/data/lanes/6090/86d33f45/source/monodroid/external/xamarin-android/external/mono/external/cecil/Mono.Cecil.PE/ImageReader.cs:759 at Mono.Cecil.ModuleDefinition.ReadModule (Mono.Disposable</code>1[T] stream, System.String fileName, Mono.Cecil.ReaderParameters parameters) [0x00008] in /Users/builder/data/lanes/6090/86d33f45/source/monodroid/external/xamarin-android/external/mono/external/cecil/Mono.Cecil/ModuleDefinition.cs:1167 at Mono.Cecil.ModuleDefinition.ReadModule (System.String fileName, Mono.Cecil.ReaderParameters parameters) [0x00078] in /Users/builder/data/lanes/6090/86d33f45/source/monodroid/external/xamarin-android/external/mono/external/cecil/Mono.Cecil/ModuleDefinition.cs:1139 at Mono.Cecil.AssemblyDefinition.ReadAssembly (System.String fileName, Mono.Cecil.ReaderParameters parameters) [0x00001] in /Users/builder/data/lanes/6090/86d33f45/source/monodroid/external/xamarin-android/external/mono/external/cecil/Mono.Cecil/AssemblyDefinition.cs:134 at Java.Interop.Tools.Cecil.DirectoryAssemblyResolver.ReadAssembly (System.String file) [0x00123] in /Users/builder/data/lanes/6090/86d33f45/source/monodroid/external/xamarin-android/external/Java.Interop/src/Java.Interop.Tools.Cecil/Java.Interop.Tools.Cecil/DirectoryAssemblyResolver.cs:170 at Java.Interop.Tools.Cecil.DirectoryAssemblyResolver.Load (System.String fileName, System.Boolean forceLoad) [0x00029] in /Users/builder/data/lanes/6090/86d33f45/source/monodroid/external/xamarin-android/external/Java.Interop/src/Java.Interop.Tools.Cecil/Java.Interop.Tools.Cecil/DirectoryAssemblyResolver.cs:136 --- End of inner exception stack trace --- at Java.Interop.Tools.Diagnostics.Diagnostic.Error (System.Int32 code, System.Exception innerException, System.String message, System.Object[] args) [0x00000] in /Users/builder/data/lanes/6090/86d33f45/source/monodroid/external/xamarin-android/external/Java.Interop/src/Java.Interop.Tools.Diagnostics/Java.Interop.Tools.Diagnostics/Diagnostic.cs:165 at Java.Interop.Tools.Cecil.DirectoryAssemblyResolver.Load (System.String fileName, System.Boolean forceLoad) [0x00034] in /Users/builder/data/lanes/6090/86d33f45/source/monodroid/external/xamarin-android/external/Java.Interop/src/Java.Interop.Tools.Cecil/Java.Interop.Tools.Cecil/DirectoryAssemblyResolver.cs:138 at Xamarin.Android.Tasks.ResolveAssemblies.ResolveRuntimeAssemblyForReferenceAssembly (NuGet.ProjectModel.LockFile lockFile, Java.Interop.Tools.Cecil.DirectoryAssemblyResolver resolver, System.String assemblyPath) [0x00151] in :0 at Xamarin.Android.Tasks.ResolveAssemblies.Execute (Java.Interop.Tools.Cecil.DirectoryAssemblyResolver resolver) [0x001ac] in :0</p>
  </blockquote>