Handle empty GameDKXboxLatest

Author: walbourn

.azuredevops/pipelines/DirectXTex-GitHub-GDK-Dev17.yml

@@ -295,13 +295,6 @@ jobs:
         parameters:
           windows: false
           scarlett: true
-      - task: PowerShell@2
-        displayName: 'NuGet Install GDK'
-        inputs:
-          targetType: filePath
-          filePath: ./build/RestoreGDK.ps1
-          arguments: -GDKEditionNumber $(GDK_EDITION) -OutputDirectory $(EXTRACTED_FOLDER)
-          failOnStderr: true
       - task: CmdLine@2
         displayName: Setup BWOI for GDK command-line
         inputs:

CMakeLists.txt

@@ -142,7 +142,7 @@ if(DEFINED XBOX_CONSOLE_TARGET)
     endif()
 
 elseif((BUILD_XBOX_EXTS_XBOXONE OR BUILD_XBOX_EXTS_SCARLETT) AND WIN32)
-    if(DEFINED ENV{GameDKXboxLatest})
+    if((DEFINED ENV{GameDKXboxLatest}) AND (NOT ("$ENV{GameDKXboxLatest}" STREQUAL "")))
         cmake_path(SET GameDK_DIR "$ENV{GameDKXboxLatest}")
     elseif(DEFINED ENV{GameDKLatest})
         cmake_path(SET GameDK_DIR "$ENV{GameDKLatest}")