ui-summary: Pass filename to about-filter

This gives the about-filter API the same semantics as source-filter,
where the filter receives the filename so it can decide what to do next
with it.

While we're at it, plug a memory leak.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

cgit.c

@@ -37,10 +37,10 @@ static struct cgit_filter *new_filter(const char *cmd, filter_type filtertype)
 
 	switch (filtertype) {
 		case SOURCE:
+		case ABOUT:
 			extra_args = 1;
 			break;
 
-		case ABOUT:
 		case COMMIT:
 		default:
 			extra_args = 0;