[uri] Allow URIs to incorporate a parameter list

HTTP POST requires the ability to associate a parameter list with a
URI.  There is no standardised syntax for this.  Use a non-standard
URI syntax to incorporate the specification of a parameter list within
a URI:

  URI = [ absoluteURI | relativeURI ]
	[ "#" fragment ] [ "##params" [ "=" paramsName ] ]

e.g.

  http://boot.ipxe.org/demo/boot.php##params
  http://boot.ipxe.org/demo/boot.php##params=mylist

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/include/ipxe/uri.h

@@ -13,6 +13,8 @@ FILE_LICENCE ( GPL2_OR_LATER );
 #include <stdlib.h>
 #include <ipxe/refcnt.h>
 
+struct parameters;
+
 /** A Uniform Resource Identifier
  *
  * Terminology for this data structure is as per uri(7), except that
@@ -65,6 +67,8 @@ struct uri {
 	const char *query;
 	/** Fragment */
 	const char *fragment;
+	/** Form parameters */
+	struct parameters *params;
 } __attribute__ (( packed ));
 
 /** A field in a URI