Fix up Mono.Android.dll path resolution on windows

The install path is different in vs2017 now, since you can have multiple vs2017 installs, so the android reference assemblies aren’t in a common folder under program files any longer.

Author: Redth

build.cake

@@ -151,8 +151,10 @@ class ArtifactInfo
 }
 
 var MONODROID_PATH = "/Library/Frameworks/Xamarin.Android.framework/Versions/Current/lib/mandroid/platforms/" + ANDROID_SDK_VERSION + "/";
-if (IsRunningOnWindows ())
-	MONODROID_PATH = MakeAbsolute (new DirectoryPath (Environment.GetFolderPath (Environment.SpecialFolder.ProgramFilesX86)).Combine ("Reference Assemblies/Microsoft/Framework/MonoAndroid/" + ANDROID_SDK_VERSION +"/")).FullPath;
+if (IsRunningOnWindows ()) {
+	var vsInstallPath = VSWhereLatest (new VSWhereLatestSettings { Requires = "Component.Xamarin" });
+	MONODROID_PATH = vsInstallPath.Combine ("Common7/IDE/ReferenceAssemblies/Microsoft/Framework/MonoAndroid/" + ANDROID_SDK_VERSION).FullPath;
+}
 
 var MSCORLIB_PATH = "/Library/Frameworks/Xamarin.Android.framework/Libraries/mono/2.1/";
 if (IsRunningOnWindows ()) {
@@ -165,6 +167,9 @@ if (IsRunningOnWindows ()) {
 		MSCORLIB_PATH = MakeAbsolute (DOTNETDIR.Combine("Framework/v4.0.30319/")).FullPath;
 }
 
+Information ("MONODROID_PATH: {0}", MONODROID_PATH);
+Information ("MSCORLIB_PATH: {0}", MSCORLIB_PATH);
+
 var nugetInfos = ARTIFACTS.Select (a => new NuGetInfo { NuSpec = "./" + a.PathPrefix + a.ArtifactId + "/nuget/" + a.NugetId + ".nuspec", Version = a.NuGetVersion, RequireLicenseAcceptance = true }).ToList ();
 nugetInfos.Add (new NuGetInfo { NuSpec = "./support-v4/nuget/Xamarin.Android.Support.v4.nuspec", Version = NUGET_VERSION, RequireLicenseAcceptance = true });