Support disabling event tracing

[cshung]

These fixes make it possible to turn off FEATURE_EVENT_TRACE during build.

@janvorli

[lateralusX]

We had a similar build issue when bringing up Android runtime builds on CoreCLR, at one point it disabled the FEATURE_EVENT_TRACE using:

<_CoreClrBuildArg Include="-cmakeargs -DFEATURE_EVENT_TRACE=0"/>

and that caused the following error:

C:\git\runtime\src\coreclr\inc\profilepriv.h(388,34): error C2061: syntax error: identifier 'EventPipeProvider' [C:\git\runtime\artifacts\obj\coreclr\windows.x64.Debug\ide\debug\daccess\daccess.vcxproj]

So looks like this PR will fix that issue!

One thought, looks like the profilepriv.h introduce the typedef typedef struct _EventPipeProvider EventPipeProvider using a different define, FEATURE_PERF_TRACING, compared to what's being used in eventpipeadaptertypes.h, FEATURE_PERFTRACING, intentional?

[lateralusX]

@cshung I had one last small comment on one define usage. Once that is adjusted do you believe this PR is ready to go?

[cshung]

@cshung I had one last small comment on one define usage.

Thanks for all the review! I will fix the last define usage.

Once that is adjusted do you believe this PR is ready to go?

From my perspective, it is ready to go.

To goal of this PR is simply to allow people to experiment with turning off FEATURE_EVENT_TRACE, so that they can try out things (e.g. try it on new architecture where code inside FEATURE_EVENT_TRACE is giving trouble). It is not meant for making sure everything works fine with that. For example, we knew some test cases that relies on tracing fails, and that is expected.

I believe the most recent "Experimentally switch off ..." commit showed that it is the case, so I think this PR acomplished its goal. Of course, we aren't going to merge that commit.