Fix "make tags" command (#1337)

Backport enhancements from master, commits:

* 9c4bfa6669e220efdd379b9f8e7db32bb4e25e72: "make tags": remove -t
  option of ctags. The option was kept for backward compatibility,
  but it was completly removed recently. Patch written by Stéphane
  Wirtel.
* cf0ac6a71ae51249a05521f49c1a0fabbb948488: Fix "make tags": set
  locale to C to call sort
* 8a543c0bc7347d5b333f334d157bf4a7cd33c14a: `make tags` fixes (GH-717)
3 files changed