Fix graph build hang on underspecified target protocols (#3855)
Fix graph build hang on underspecified target protocols (#3855)

The code skips a node when no targets are provided. This skipping though needs to set the event to make the loop going again.
sean-gilliam/msbuild,rainersigwald/msbuild,cdmihai/msbuild,sean-gilliam/msbuild,chipitsine/msbuild,mono/msbuild,AndyGerlicher/msbuild,cdmihai/msbuild,AndyGerlicher/msbuild,cdmihai/msbuild,Microsoft/msbuild,mono/msbuild,jeffkl/msbuild,chipitsine/msbuild,AndyGerlicher/msbuild,mono/msbuild,Microsoft/msbuild,AndyGerlicher/msbuild,jeffkl/msbuild,Microsoft/msbuild,rainersigwald/msbuild,sean-gilliam/msbuild,rainersigwald/msbuild,Microsoft/msbuild,chipitsine/msbuild,cdmihai/msbuild,mono/msbuild,sean-gilliam/msbuild,chipitsine/msbuild,jeffkl/msbuild,rainersigwald/msbuild,jeffkl/msbuild