VS2017 Add some debug messages for Appveyor as build failing

Author: amaitland

build.ps1

@@ -214,6 +214,8 @@ function Msvs
             #Check if we already have vswhere which is included in newer versions of VS2017
             if(-not (Test-Path $vswherePath))
             {
+				Write-Diagnostic "Downloading VSWhere as no install found at $vswherePath"
+				
                 # Check if we already have a local copy and download if required
                 $vswherePath = Join-Path $WorkingDir \vswhere.exe
 
@@ -224,9 +226,15 @@ function Msvs
                     $client.DownloadFile('https://github.com/Microsoft/vswhere/releases/download/2.2.11/vswhere.exe', $vswherePath);
                 }
             }
+			
+			Write-Diagnostic "VSWhere path $vswherePath"
+			
             $VS2017InstallPath = & $vswherePath -version 15 -property installationPath
+			
+			Write-Diagnostic "VS2017InstallPath: $VS2017InstallPath"
 
-            if(-not (Test-Path $VS2017InstallPath)) {
+            if(-not (Test-Path $VS2017InstallPath))
+			{
                 Die "Visual Studio 2017 was not found"
             }