cmd/ld: handle IMAGE_SYM_CLASS_LABEL symbols. Was causing "invalid symbol binding" and thus "malformed pe file" error.
cmd/ld: handle IMAGE_SYM_CLASS_LABEL symbols.
Was causing "invalid symbol binding" and thus "malformed pe file" error.

R=golang-dev, alex.brainman, adg
CC=golang-dev
https://codereview.appspot.com/13722050

h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang