Update gsoup to 2.7.17.
Based on PR#43789 by Kamel Derouiche.

pkgsrc changes:
 * install documentation additionally.
 * exactly buildlink with zlib and openssl.

upstream changes:

# Version 2.7.14 (09/07/2009)

    * Added support for poll() to replace select() to prevent FD_EXCEEDED.
    * Fixed enum local simpleType restriction attribute initialization.
    * Fixed utf8 string parsing issue when first char in CDATA could cause
      problems.
    * Fixed UDP IPv6 multicast-unicast exchange.
    * Fixed gzip end-of-stream check.
    * Fixed wsdl2h portType operation-input/output matching to ensure operations
      can be safely overloaded.

# Version 2.7.15 (11/07/2009)

    * Added soap_read_X() and soap_write_X() macros to simplify object reading
      and writing.
    * Fixed soap_new_X() functions compilation problem.
    * Fixed SSL session in context copy.
    * Fixed win32 select() in tcp_select().
    * Fixed wstrings in unions.
    * Fixed preservation of CDATA sections in literal XML strings.

# Version 2.7.16 (04/05/2010)

    * Added soapcpp2 option -T to generate auto-test echo server code with an
      example in samples/autotest based on 294 patterns for data binding W3C
      workgroup.
    * Added soapcpp2 option -b to serialize byte arrays char[] as fixed-size
      strings (array of xsd:byte otherwise).
    * Added xsd:duration serializer: import custom/duration.h.
    * Added gsoap header syntax '$' type qualifier to indicate special
      struct/class members (array length, union discriminators).
    * Added "colon notation" to attach XML prefixes to C/C++ names without
      changing the names, an alternative to the ns__ prefix notation.
    * Added wsdl2h options -z# for backward compatibility flags (-z1, -z2).
    * Added SOAP_XML_IGNORENS to optionally ignore XML namespaces.
    * Added WS-ReliableMessaging plugin.
    * Added custom xsd:duration serializer.
    * Added WSSE plugin soap_wsse_set_wsu_id() to simplify signing of elements
      (sets the wsu:Id of a given element tag name).
    * Improved handling of struct/class member name clashes resulting from XML
      schemas definitions.
    * Improved SOAP RPC ecoding response element tag acceptance.
    * Improved VxWorks compatibility.
    * Fixed FastCGI SOAP/XML processing with MIME attachments.
    * Fixed 'typedef std::string XML', for literal XML serialization problem.
    * Fixed a rare incorrect well-formedness error when xmlns default namespaces
      are absent.
    * Fixed a zlib compression error when obsolete crc check is used.
    * Fixed WS-Addressing HTTPS message relay (OpenSSL crash).

# Version 2.7.17 (05/10/2010)

    * Added WS-Policy 1.2 and 1.5, WS-SecurityPolicy 1.2 support for wsdl2h.
    * Improved WS-ReliableMessaging interop and verified MT-safety.
    * Improved WS-Security WSSE plugin documentation.
    * Fixed soapcpp2 line number error reporting.
    * Fixed WSSE plugin soap_wsse_set_wsu_id().
    * Fixed wsdl2h cycle problem with recursive xs:include and xs:import.
    * Fixed enum translation of enum symbols with colons.
    * Fixed std::wstring used as XML attribute value UTF8 encoding (internal stdsoap2 API changed).


(obache)