Do not allocate in TaskItem.GetHashCode
Do not allocate in TaskItem.GetHashCode

This was causing about 0.3% of allocations (12 MB) of a particular scenario installing NuGet packages.

chipitsine/msbuild,cdmihai/msbuild,cdmihai/msbuild,Microsoft/msbuild,Microsoft/msbuild,AndyGerlicher/msbuild,cdmihai/msbuild,sean-gilliam/msbuild,Microsoft/msbuild,rainersigwald/msbuild,mono/msbuild,chipitsine/msbuild,AndyGerlicher/msbuild,Microsoft/msbuild,rainersigwald/msbuild,AndyGerlicher/msbuild,sean-gilliam/msbuild,sean-gilliam/msbuild,mono/msbuild,jeffkl/msbuild,cdmihai/msbuild,sean-gilliam/msbuild,jeffkl/msbuild,mono/msbuild,jeffkl/msbuild,rainersigwald/msbuild,chipitsine/msbuild,chipitsine/msbuild,jeffkl/msbuild,AndyGerlicher/msbuild,mono/msbuild,rainersigwald/msbuild