Update vs15.8 IBCMerge branch (#3492)
Update vs15.8 IBCMerge branch (#3492)


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