Merge branch 'jc/url-match'

Merge branch 'jc/url-match'

Allow section.<urlpattern>.var configuration variables to be
treated as a "virtual" section.var given a URL, and use the
mechanism to enhance http.* configuration variables.

This is a reroll of Kyle J. McKay's work.

* jc/url-match:
  builtin/config.c: compilation fix
  config: "git config --get-urlmatch" parses section.<url>.key
  builtin/config: refactor collect_config()
  config: parse http.<url>.<variable> using urlmatch
  config: add generic callback wrapper to parse section.<url>.key
  config: add helper to normalize and match URLs
  http.c: fix parsing of http.sslCertPasswordProtected variable