urlmatch: split host and port fields in `struct url_info`

The `url_info` structure contains information about a normalized URL
with the URL's components being represented by different fields. The
host and port part though are to be accessed by the same `host` field,
so that getting the host and/or port separately becomes more involved
than really necessary.

To make the port more readily accessible, split up the host and port
fields. Namely, the `host_len` will not include the port length anymore
and a new `port_off` field has been added which includes the offset to
the port, if available.

The only user of these fields is `url_normalize_1`. This change makes it
easier later on to treat host and port differently when introducing
globs for domains.

Signed-off-by: Patrick Steinhardt <patrick.steinhardt@elego.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/urlmatch.h b/urlmatch.h
index 528862a..0ea812b 100644
--- a/urlmatch.h
+++ b/urlmatch.h
@@ -18,11 +18,12 @@ struct url_info {
 	size_t passwd_len;	/* length of passwd; if passwd_off != 0 but
 				   passwd_len == 0, an empty passwd was given */
 	size_t host_off;	/* offset into url to start of host name (0 => none) */
-	size_t host_len;	/* length of host name; this INCLUDES any ':portnum';
+	size_t host_len;	/* length of host name;
 				 * file urls may have host_len == 0 */
-	size_t port_len;	/* if a portnum is present (port_len != 0), it has
-				 * this length (excluding the leading ':') at the
-				 * end of the host name (always 0 for file urls) */
+	size_t port_off;	/* offset into url to start of port number (0 => none) */
+	size_t port_len;	/* if a portnum is present (port_off != 0), it has
+				 * this length (excluding the leading ':') starting
+				 * from port_off (always 0 for file urls) */
 	size_t path_off;	/* offset into url to the start of the url path;
 				 * this will always point to a '/' character
 				 * after the url has been normalized */