set TreatWarningsAsErrors to true (#1897)

* set TreatWarningsAsErrors to true to ensure that no new warnings are being added

* solve the only warning we have

Author: adamsitnik

build/common.props

@@ -18,6 +18,7 @@
     <UseSharedCompilation>false</UseSharedCompilation>
     <SuppressNETCoreSdkPreviewMessage>True</SuppressNETCoreSdkPreviewMessage>
     <CodeAnalysisRuleSet>$(MSBuildThisFileDirectory)CodingStyle.ruleset</CodeAnalysisRuleSet>
+    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
   </PropertyGroup>
 
   <ItemGroup>

src/BenchmarkDotNet.Diagnostics.Windows/EtwProfilerConfig.cs

@@ -18,6 +18,7 @@ public class EtwProfilerConfig
         public float CpuSampleIntervalInMilliseconds { get; }
 
         public KernelTraceEventParser.Keywords KernelKeywords { get; }
+
         public KernelTraceEventParser.Keywords KernelStackKeywords { get; }
 
         public IReadOnlyDictionary<HardwareCounter, Func<ProfileSourceInfo, int>> IntervalSelectors { get; }
@@ -31,6 +32,7 @@ public class EtwProfilerConfig
         /// <param name="cpuSampleIntervalInMilliseconds">The rate at which CPU samples are collected. By default this is 1 (once a millisecond per CPU). There is a lower bound on this (typically 0.125 ms)</param>
         /// <param name="intervalSelectors">interval per hardware counter, if not provided then default values will be used.</param>
         /// <param name="kernelKeywords">kernel session keywords, ImageLoad (for native stack frames) and Profile (for CPU Stacks) are the defaults</param>
+        /// <param name="kernelStackKeywords">This is passed to TraceEventSession.EnableKernelProvider to enable particular sets of events. See https://docs.microsoft.com/windows/win32/api/evntrace/ns-evntrace-event_trace_properties#members for more information on them.</param>
         /// <param name="providers">providers that should be enabled, if not provided then default values will be used</param>
         /// <param name="createHeapSession">value indicating whether to create heap session. False by default, used internally by NativeMemoryProfiler.</param>
         public EtwProfilerConfig(