Improve default build times on arm64

[rolfbjarne]

The default build times for a Mac Catalyst app on arm64 are horrendous:

• dotnet new maccatalyst && dotnet build: 1 minute

Enabling the trimmer or the interpreter makes it much better:

• dotnet new maccatalyst && dotnet build /p:UseInterpreter: 17 seconds
• dotnet new maccatalyst && dotnet build /p:TrimMode=partial: 12 seconds
• dotnet new maccatalyst && dotnet build /p:TrimMode=full: 12 seconds
• dotnet new maccatalyst && dotnet build /p:TrimMode=partial /p:UseInterpreter=true: 12 seconds

So I suggest we enable the trimmer by default for Debug mode on Mac Catalyst (this would match how we handle iOS and tvOS in the simulator + we don't enable the interpreter on any other platform).

The same thing happens for the iOS and tvOS Simulators as well.

[tipa]

In tests with my real-world apps, build + deploy times to the simulator are ~16 seconds when only specifying UseInterpreter and ~13-14 seconds when specifying both UseInterpreter & TrimMode=partial. Will this change yield similar results? I am asking because in the commit it says

Linking is on by default in the simulator when building for arm64, as long as the interpreter is not enabled

https://github.com/xamarin/xamarin-macios/blob/bc1ae55783c0e0ceb419e9b103b2b09201b9faf8/dotnet/targets/Xamarin.Shared.Sdk.Trimming.props#L57C1-L58C1

[rolfbjarne]

In tests with my real-world apps, build + deploy times to the simulator are ~16 seconds when only specifying UseInterpreter and ~13-14 seconds when specifying both UseInterpreter & TrimMode=partial. Will this change yield similar results? I am asking because in the commit it says

Linking is on by default in the simulator when building for arm64, as long as the interpreter is not enabled

bc1ae55/dotnet/targets/Xamarin.Shared.Sdk.Trimming.props#L57C1-L58C1

Yes, you should get some similar results (probably somewhere between 13 and 16 seconds).

It should be easy enough for you to try it, by building with "TrimMode=partial" (without setting UseInterpreter).

[tipa]

Only tested with one app, but the build & deploy time to simulator increased from 16 seconds to 21 seconds when removing UseInterpreter=false and using TrimMode=partial only