Fix macOS build

staticcheck used to fail on macOS (and presumably windows) due to a
variable declared in a common package that was only used by the Linux
build, which would prevent `redo pr` from passing on Mac. Moved variable
declaration from the common file to the Linux-specific one to resolve
the compiler complaint.

Signed-off-by: Wendi Yu <wendi.yu@yahoo.ca>

portlist/portlist.go

@@ -21,8 +21,6 @@ type Port struct {
 // List is a list of Ports.
 type List []Port
 
-var protos = []string{"tcp", "udp"}
-
 func (a *Port) lessThan(b *Port) bool {
 	if a.Port < b.Port {
 		return true