Merge branch 'jk/remote-wo-url'

Merge branch 'jk/remote-wo-url'

Memory ownership rules for the in-core representation of
remote.*.url configuration values have been straightened out, which
resulted in a few leak fixes and code clarification.

* jk/remote-wo-url:
  remote: drop checks for zero-url case
  remote: always require at least one url in a remote
  t5801: test remote.*.vcs config
  t5801: make remote-testgit GIT_DIR setup more robust
  remote: allow resetting url list
  config: document remote.*.url/pushurl interaction
  remote: simplify url/pushurl selection
  remote: use strvecs to store remote url/pushurl
  remote: transfer ownership of memory in add_url(), etc
  remote: refactor alias_url() memory ownership
  archive: fix check for missing url