Move cgit_repo into cgit_context

This removes the global variable which is used to keep track of the
currently selected repository, and adds a new variable in the cgit_context
structure.

Signed-off-by: Lars Hjemli <hjemli@gmail.com>
diff --git a/ui-commit.c b/ui-commit.c
index 3b0919b..25721ca 100644
--- a/ui-commit.c
+++ b/ui-commit.c
@@ -194,10 +194,10 @@
 			       sha1_to_hex(p->item->object.sha1), NULL);
 		html(")</td></tr>");
 	}
-	if (cgit_repo->snapshots) {
+	if (ctx.repo->snapshots) {
 		html("<tr><th>download</th><td colspan='2' class='sha1'>");
 		cgit_print_snapshot_links(ctx.qry.repo, ctx.qry.head,
-					  hex, cgit_repo->snapshots);
+					  hex, ctx.repo->snapshots);
 		html("</td></tr>");
 	}
 	html("</table>\n");