patches.rb: Generalize File recognition

Extend patch case statements for files to objects inheriting from `IO`, which
includes `File`, or `StringIO` which is used by the external command
`brew-unpack` to store `DATA` sections loaded from Formula files.

Library/Homebrew/patches.rb

@@ -1,3 +1,5 @@
+require 'stringio'
+
 class Patches
   include Enumerable
 
@@ -72,7 +74,8 @@ class Patch
     @compression = nil
     @url = nil
 
-    if url.kind_of? File # true when DATA is passed
+    if url.kind_of? IO or url.kind_of? StringIO
+      # File-like objects. Most common when DATA is passed.
       write_data url
     elsif looks_like_url(url)
       @url = url # Save URL to mark this as an external patch