The "curl" executable is no longer required

git-clone.sh was the last user of the "curl" executable. Relevant git
commands now use libcurl instead. This should be reflected in the
install requirements.

Signed-off-by: Johan Herland <johan@herland.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

INSTALL

@@ -67,10 +67,10 @@ Issues of note:
 	  that come with git (git includes the one from Mozilla, and has
 	  its own PowerPC and ARM optimized ones too - see the Makefile).
 
-	- "libcurl" and "curl" executable.  git-http-fetch and
-	  git-fetch use them.  If you do not use http
-	  transfer, you are probably OK if you do not have
-	  them.
+	- libcurl library; git-http-fetch and git-fetch use them.  You
+	  might also want the "curl" executable for debugging purposes.
+	  If you do not use http transfer, you are probably OK if you
+	  do not have them.
 
 	- expat library; git-http-push uses it for remote lock
 	  management over DAV.  Similar to "curl" above, this is optional.