Sdk: Change dotnet build to create portable pdbs by default

[sayedihashimi]

The current experience for VS Code users is not ideal for debugging when running on Mac/Linux because you cannot step into a break point until you update project.json to produce portable pdbs by default.

When dotnet build is executed it should produce portable pdbs by default if it's not already configured in project.json.

Related to dotnet/sdk#6341

[TheRealPiotrP]

Why is 1.1 the right milestone here? If we mean Runtime 1.1, that will likely map to CLI preview3 or RTM.

[sayedihashimi]

I may not have set the right milestone, please update if I got it wrong.

[smbecker]

My vote would be to not do this. Changing to portable pdbs caused issues debugging in Visual Studio on Windows. I get that you want to enable cross-platform but a large majority of developers still use Visual Studio.

[eerhardt]

Changing to portable pdbs caused issues debugging in Visual Studio on Windows

Can you elaborate on the issues? Also, shouldn't we be fixing those issues in Visual Studio?

[smbecker]

Stack traces never include line numbers of source files and locals and immediate windows were incredibly flakey.

I agree that those should be fixed in VS but until they are...

[livarcocc]

Our templates are using portable pdbs by default.