Removed redundant shell script

build/BuildBenchmark.ps1

-write-host `nRunning build. Please wait...
-
-$iterations = 10
-
-for ($i=1; $i -le $iterations; $i++)
-{
-	$sw = [System.Diagnostics.StopWatch]::StartNew()
-	& E:\dotnet-protobufs\build\BuildAll.bat
-	$sw.Stop()
-	$msbuildTotalRunTime += $sw.ElapsedMilliseconds
-}
-
-write-host `nMSBuild average speed over $iterations iterations: ($msbuildTotalRunTime/$iterations) milliseconds
\ No newline at end of file