Fix cake on vs2017 4.8. 0 (#13697)

* Fix arguments vs2017

* Install dotnet before using cake

build.cake

@@ -111,7 +111,7 @@ string MSBuildArgumentsARGS = Argument("MSBuildArguments", "");
 string MSBuildArguments;
 
 if(buildForVS2017)
-    MSBuildArguments = String.Empty;
+    MSBuildArguments = " ";
 else
     MSBuildArguments = $"{MSBuildArgumentsENV} {MSBuildArgumentsARGS}";
     

build/steps/build-android.yml

@@ -44,6 +44,13 @@ jobs:
       - checkout: self
         clean: true
 
+      - task: UseDotNet@2
+        displayName: 'Install .net core $(DOTNET_VERSION)'
+        condition: ne(variables['DOTNET_VERSION'], '')
+        inputs:
+          version: $(DOTNET_VERSION)
+          packageType: 'sdk'
+
       - task: Bash@3
         displayName: 'Cake Provision'
         condition: or(eq(variables['provisioningCake'], 'true'), eq(variables['buildForVS2017'], 'true'))
@@ -59,13 +66,6 @@ jobs:
           provisioning_script: ${{ parameters.provisionatorPath }}
           provisioning_extra_args: ${{ parameters.provisionator.extraArguments }}
 
-      - task: UseDotNet@2
-        displayName: 'Install .net core $(DOTNET_VERSION)'
-        condition: ne(variables['DOTNET_VERSION'], '')
-        inputs:
-          version: $(DOTNET_VERSION)
-          packageType: 'sdk'
-
       - script: '/bin/bash -c "sudo $AGENT_HOMEDIRECTORY/scripts/select-xamarin-sdk.sh ${{ parameters.monoVersion }}"'
         displayName: 'Select MONO ${{ parameters.monoVersion }}'