Adding a simple performance test for Span+Slice vs Slice+Span (#1353)
Adding a simple performance test for Span+Slice vs Slice+Span (#1353)

* Adding a simple performance test for Span+Slice vs Slice+Span

* Simpifying the test a bit; introducing randomness to help avoid optimization

joshfree/corefxlab,tarekgh/corefxlab,KrzysztofCwalina/corefxlab,Vedin/corefxlab,stephentoub/corefxlab,whoisj/corefxlab,Vedin/corefxlab,ahsonkhan/corefxlab,hanblee/corefxlab,joshfree/corefxlab,ericstj/corefxlab,stephentoub/corefxlab,ahsonkhan/corefxlab,VSadov/corefxlab,dotnet/corefxlab,ericstj/corefxlab,VSadov/corefxlab,VSadov/corefxlab,KrzysztofCwalina/corefxlab,VSadov/corefxlab,ericstj/corefxlab,ericstj/corefxlab,stephentoub/corefxlab,adamsitnik/corefxlab,whoisj/corefxlab,stephentoub/corefxlab,VSadov/corefxlab,tarekgh/corefxlab,adamsitnik/corefxlab,hanblee/corefxlab,benaadams/corefxlab,stephentoub/corefxlab,dotnet/corefxlab,benaadams/corefxlab,ericstj/corefxlab,ericstj/corefxlab,Vedin/corefxlab,VSadov/corefxlab,stephentoub/corefxlab,Vedin/corefxlab,Vedin/corefxlab,Vedin/corefxlab