Merge pull request dotnet/coreclr#9598 from ahsonkhan/OptimizeSpanClear

Optimize span clear

Commit migrated from https://github.com/dotnet/coreclr/commit/da44463552689930c4d4ead5aa01a437fcbea622

diff --cc src/coreclr/src/mscorlib/System.Private.CoreLib.csproj
Simple merge

diff --cc src/coreclr/src/mscorlib/src/System/Span.cs
Simple merge

diff --cc src/coreclr/src/vm/ecalllist.h
Simple merge

diff --cc src/coreclr/src/vm/jitinterface.cpp
Simple merge

diff --cc src/coreclr/src/vm/mscorlib.h
Simple merge