small change so that the version number makes more sense

Slackware/i2p/i2p.SlackBuild

@@ -28,9 +28,9 @@ ARCH=noarch
 # This mess is here due to the totally moronic way i2p does versioning.
 # We correct it here.
 #
-ROUTER=$(echo -ne "-")$(cat ../../router/java/src/net/i2p/router/RouterVersion.java | grep -e "public final static long BUILD" | cut -f2 -d"=" | cut -f1 -d";" | sed -re "s/ //g")
-if [ "$ROUTER" == "-" ] ;  then
-	ROUTER="-0"
+ROUTER=$(echo -ne "_")$(cat ../../router/java/src/net/i2p/router/RouterVersion.java | grep -e "public final static long BUILD" | cut -f2 -d"=" | cut -f1 -d";" | sed -re "s/ //g")
+if [ "$ROUTER" == "_" ] ;  then
+	ROUTER="_0"
 fi
 
 #