Log Message:
Update www/php-http to 2.6.0.

- Added http\Client\Curl\User interface for userland event loops
- Added http\Url::IGNORE_ERRORS, http\Url::SILENT_ERRORS and
  http\Url::STDFLAGS
- Added http\Client::setDebug(callable $debug)
- Added http\Client\Curl\FEATURES constants and namespace
- Added http\Client\Curl\VERSIONS constants and namespace
- Added share_cookies and share_ssl (libcurl >= 7.23.0) options to
  http\Client::configure()
- http\Client uses curl_share handles to properly share cookies and
  SSL/TLS sessions between requests
- Improved configure checks for default CA bundles
- Improved negotiation precision
- Fixed regression introduced by http\Params::PARSE_RFC5987:
  negotiation using the params parser would receive param keys without
  the trailing asterisk, stripped by http\Params::PARSE_RFC5987.
- Fix gh-issue #50: http\Client::dequeue() within
  http\Client::setDebug() causes segfault
- Fix gh-issue #47: http\Url: Null pointer deref in sanitize_value()
- Fix gh-issue #45: HTTP/2 response message parsing broken with
  libcurl >= 7.49.1
- Fix gh-issue #43: Joining query with empty original variable in
  query
- Fix gh-issue #42: fatal error when using punycode in URLs
- Fix gh-issue #41: Use curl_version_info_data.features when
  initializing options
- Fix gh-issue #40: determinde the SSL backend used by curl at runtime
- Fix gh-issue #39: Notice: http\Client::enqueue(): Could not set
  option proxy_service_name
- Fix gh-issue #38: Persistent curl handles: error code not properly
  reset
- Fix gh-issue #36: Unexpected cookies sent if persistent_handle_id is
  used
- Fix gh-issue #34: allow setting multiple headers with the same name
- Fix gh-issue #33: allow setting prodyhost request option to NULL
- Fix gh-issue #31: add/improve configure checks for default CA
  bundle/path

Changes from beta1:
- Fixed PHP-5.3 compatibility
- Fixed recursive calls to the event loop dispatcher

Changes from beta2:
- Fix bug #73055: crash in http\QueryString (CVE-2016-7398)
- Fix bug #73185: Buffer overflow in HTTP parse_hostinfo()
  (CVE-2016-7961)
- Fix HTTP/2 version parser for older libcurl versions