Fix pack.cmd ERRORLEVEL early exits
Fix pack.cmd ERRORLEVEL early exits

"if ERRORLEVEL x" runs if ERRORLEVEL >= x. "if not ERRORLEVEL 0" means ERRORLEVEL < 0, which doesn't detect the error we get. "if ERRORLEVEL 1" is idiomatic in cmd, but to catch negative ERRORLEVEL, use string matching on the ERRORLEVEL variable.

Also added early exits on steps that didn't have one.

MichaelSimons/core-setup,ericstj/core-setup,wtgodbe/core-setup,zamont/core-setup,ravimeda/core-setup,ramarag/core-setup,steveharter/core-setup,gkhanna79/core-setup,chcosta/core-setup,weshaggard/core-setup,weshaggard/core-setup,joperezr/core-setup,chcosta/core-setup,janvorli/core-setup,vivmishra/core-setup,ericstj/core-setup,rakeshsinghranchi/core-setup,chcosta/core-setup,crummel/dotnet_core-setup,weshaggard/core-setup,rakeshsinghranchi/core-setup,crummel/dotnet_core-setup,crummel/dotnet_core-setup,ramarag/core-setup,crummel/dotnet_core-setup,steveharter/core-setup,wtgodbe/core-setup,crummel/dotnet_core-setup,zamont/core-setup,janvorli/core-setup,janvorli/core-setup,ramarag/core-setup,steveharter/core-setup,gkhanna79/core-setup,gkhanna79/core-setup,joperezr/core-setup,joperezr/core-setup,joperezr/core-setup,janvorli/core-setup,ramarag/core-setup,zamont/core-setup,vivmishra/core-setup,zamont/core-setup,joperezr/core-setup,gkhanna79/core-setup,gkhanna79/core-setup,crummel/dotnet_core-setup,janvorli/core-setup,steveharter/core-setup,steveharter/core-setup,weshaggard/core-setup,ravimeda/core-setup,ravimeda/core-setup,ravimeda/core-setup,ravimeda/core-setup,wtgodbe/core-setup,steveharter/core-setup,ericstj/core-setup,weshaggard/core-setup,chcosta/core-setup,wtgodbe/core-setup,weshaggard/core-setup,MichaelSimons/core-setup,MichaelSimons/core-setup,vivmishra/core-setup,chcosta/core-setup,ramarag/core-setup,wtgodbe/core-setup,joperezr/core-setup,rakeshsinghranchi/core-setup,rakeshsinghranchi/core-setup,ramarag/core-setup,chcosta/core-setup,janvorli/core-setup,vivmishra/core-setup,ericstj/core-setup,gkhanna79/core-setup,rakeshsinghranchi/core-setup,ericstj/core-setup,rakeshsinghranchi/core-setup,ravimeda/core-setup,vivmishra/core-setup,ericstj/core-setup,wtgodbe/core-setup,zamont/core-setup,vivmishra/core-setup,zamont/core-setup,MichaelSimons/core-setup,MichaelSimons/core-setup,MichaelSimons/core-setup