Move userAgent to peer where it's used.

btcd.go

@@ -19,8 +19,6 @@ import (
 	"time"
 )
 
-var userAgent = fmt.Sprintf("/btcd:%d.%d.%d/", appMajor, appMinor, appPatch)
-
 // used by the dns seed code to pick a random last seen time
 const (
 	secondsIn3Days int32 = 24 * 60 * 60 * 3

peer.go

@@ -20,6 +20,10 @@ import (
 
 const outputBufferSize = 50
 
+// userAgent is the user agent string used to identify ourselves to other
+// bitcoin peers.
+var userAgent = fmt.Sprintf("/btcd:%d.%d.%d/", appMajor, appMinor, appPatch)
+
 // zeroHash is the zero value hash (all zeros).  It is defined as a convenience.
 var zeroHash btcwire.ShaHash