Support disabling event tracing

[cshung]

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

Note: the actual disabling of FEATURE_EVENT_TRACE is just a test, do NOT merge that.

@janvorli

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[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?