Improve xbps_end() and use it before exit(3)ing.

- Simplify xbps_repo_open::repo_get_dict().
- Use xbps_end() in the utils where necessary.
- Make xbps_end() call xbps_pkgdb_unlock() if necessary.
- Make xbps_end() release rpool resources.
- Make xbps_end() release resources from xbps_handle.
- Fixed 90% of reported leaks (still reachable at exit) from valgrind.

That was to silence valgrind's memcheck with --leak-check=full.

bin/xbps-reconfigure/main.c

@@ -1,5 +1,5 @@
 /*-
- * Copyright (c) 2012-2014 Juan Romero Pardines.
+ * Copyright (c) 2012-2015 Juan Romero Pardines.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -182,6 +182,6 @@ main(int argc, char **argv)
 			}
 		}
 	}
-	xbps_pkgdb_unlock(&xh);
+	xbps_end(&xh);
 	exit(rv ? EXIT_FAILURE : EXIT_SUCCESS);
 }