Ahah! Figured it out. Thanks to reading the fine manual at https://golang.org/cmd/cgo/. This syntax works:
#cgo LDFLAGS: -lm #cgo (linux OR darwin) LDFLAGS: -ldl > -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.