Correctly Save GC Mode on Suspension on Windows for SampleProfiler

[josalem]

Fixes #45179

Move SaveGCModeOnSuspension to shared location rather than Unix only code path.

Before this change (as described in #45179), all events from the SampleProfiler on Windows would be marked as UNMANAGED_CODE_TIME samples. This was intended to only be the case for when a sample was collected while native code was on the stack.

This should make samples show up correctly in PerfView.

CC @tommcdon @noahfalk @brianrob

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Issue Details

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Fixes #45179

Move SaveGCModeOnSuspension to shared location rather than Unix only code path.

Before this change (as described in #45179), all events from the SampleProfiler on Windows would be marked as UNMANAGED_CODE_TIME samples. This was intended to only be the case for when a sample was collected while native code was on the stack.

This should make samples show up correctly in PerfView.

CC @tommcdon @noahfalk @brianrob

Author:	josalem
Assignees:	josalem
Labels:	area-Diagnostics-coreclr
Milestone:	7.0.0

[josalem]

Sample of the fixed behavior (left is before, right is after):

The code traced:

using System;
using System.Threading;
using System.Runtime.CompilerServices;

[MethodImpl(MethodImplOptions.NoInlining)]
int Foo(int bar) => bar + 1;

Console.WriteLine($"PID: {System.Diagnostics.Process.GetCurrentProcess().Id}");


while (true)
{
	// Should split unmanaged and managed suspensions about 50/50
    int i = 0;
    Thread.Sleep(TimeSpan.FromSeconds(1));
    DateTime then = DateTime.Now;
    while (DateTime.Now - then < TimeSpan.FromSeconds(1))
    {
        i = Foo(i);
    }
}