INSTALL: no need to have GNU diff installed

Since a long time, we have inbuilt diff generation.
Signed-off-by: NJohannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

INSTALL

@@ -72,16 +72,6 @@ Issues of note:
 	- expat library; git-http-push uses it for remote lock
 	  management over DAV.  Similar to "curl" above, this is optional.
 
-	- "GNU diff" to generate patches.  Of course, you don't _have_ to
-	  generate patches if you don't want to, but let's face it, you'll
-	  be wanting to. Or why did you get git in the first place?
-
-	  Non-GNU versions of the diff/patch programs don't generally support
-	  the unified patch format (which is the one git uses), so you
-	  really do want to get the GNU one.  Trust me, you will want to
-	  do that even if it wasn't for git.  There's no point in living
-	  in the dark ages any more. 
-
         - "wish", the Tcl/Tk windowing shell is used in gitk to show the
           history graphically