appveyor: fix build by adding Rtools

mrustl · mrustl · commit 2cfc2ce119ad · 2019-03-14T08:07:13.000+01:00
diff --git a/appveyor.yml b/appveyor.yml
@@ -15,6 +15,9 @@ cache:
 
 # Adapt as necessary starting from here
 
+environment:
+  USE_RTOOLS: true
+
 build_script:
   - travis-tool.sh install_deps
 
