ext/socket/ifaddr.c: [DOC] fix typo

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@60705 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ext/socket/ifaddr.c

@@ -262,7 +262,7 @@ ifaddr_dstaddr(VALUE self)
  *   ifaddr.vhid => Integer
  *
  * Returns the vhid address of _ifaddr_.
- * nil is returned if there is no vhid
+ * nil is returned if there is no vhid.
  */
 
 static VALUE