ui-shared: remove toggle_ssdiff arg to cgit_commit_link()

This argument is never used with a value other than zero, so remove it
and simplify the code.

Signed-off-by: John Keeping <john@keeping.me.uk>
diff --git a/ui-log.c b/ui-log.c
index bcdb666..ad2f5fc 100644
--- a/ui-log.c
+++ b/ui-log.c
@@ -90,7 +90,7 @@
 			strncpy(buf, deco->name, sizeof(buf) - 1);
 			cgit_commit_link(buf, NULL, "deco", ctx.qry.head,
 					 sha1_to_hex(commit->object.sha1),
-					 ctx.qry.vpath, 0);
+					 ctx.qry.vpath);
 		}
 next:
 		deco = deco->next;
@@ -165,7 +165,7 @@
 		}
 	}
 	cgit_commit_link(info->subject, NULL, NULL, ctx.qry.head,
-			 sha1_to_hex(commit->object.sha1), ctx.qry.vpath, 0);
+			 sha1_to_hex(commit->object.sha1), ctx.qry.vpath);
 	show_commit_decorations(commit);
 	html("</td><td>");
 	cgit_open_filter(ctx.repo->email_filter, info->author_email, "log");