GSF.POSIX: Changed PAM authentication to use "login" service since this is predefined on OS X.
GSF.POSIX: Changed PAM authentication to use "login" service since this is predefined on OS X.

git-tfs-id: [https://tfs.codeplex.com/tfs/TFS07]$/gsf/Main;C94003

GridProtectionAlliance/gsf,GridProtectionAlliance/gsf,GridProtectionAlliance/gsf,rmc00/gsf,rmc00/gsf,rmc00/gsf,GridProtectionAlliance/gsf,rmc00/gsf,rmc00/gsf,rmc00/gsf,GridProtectionAlliance/gsf,GridProtectionAlliance/gsf,rmc00/gsf,GridProtectionAlliance/gsf,GridProtectionAlliance/gsf