Update php71 to 7.1.8.

* pkgsrc change: enable readline PKG_OPTIONS default.

03 Aug 2017, PHP 7.1.8

- Core:
  . Fixed bug #74832 (Loading PHP extension with already registered function
    name leads to a crash). (jpauli)
  . Fixed bug #74780 (parse_url() broken when query string contains colon).
    (jhdxr)
  . Fixed bug #74761 (Unary operator expected error on some systems). (petk)
  . Fixed bug #73900 (Use After Free in unserialize() SplFixedArray). (nikic)
  . Fixed bug #74923 (Crash when crawling through network share). (Anatol)
  . Fixed bug #74913 (fixed incorrect poll.h include). (petk)
  . Fixed bug #74906 (fixed incorrect errno.h include). (petk)

- Date:
  . Fixed bug #74852 (property_exists returns true on unknown DateInterval
    property). (jhdxr)

- OCI8:
  . Fixed bug #74625 (Integer overflow in oci_bind_array_by_name). (Ingmar Runge)

- Opcache:
  . Fixed bug #74623 (Infinite loop in type inference when using HTMLPurifier).
    (nikic)

- OpenSSL:
. Fixed bug #74798 (pkcs7_en/decrypt does not work if \x0a is used in content).
  (Anatol)
. Added OPENSSL_DONT_ZERO_PAD_KEY constant to prevent key padding and fix bug
  #71917 (openssl_open() returns junk on envelope < 16 bytes) and bug #72362
  (OpenSSL Blowfish encryption is incorrect for short keys). (Jakub Zelenka)

- PDO:
  . Fixed bug #69356 (PDOStatement::debugDumpParams() truncates query). (Adam
    Baratz)

- SPL:
  . Fixed bug #73471 (PHP freezes with AppendIterator). (jhdxr)

- SQLite3:
  . Fixed bug #74883 (SQLite3::__construct() produces "out of memory" exception
    with invalid flags). (Anatol)

- Wddx:
  . Fixed bug #73173 (huge memleak when wddx_unserialize).
    (tloi at fortinet dot com)

- zlib:
  . Fixed bug #73944 (dictionary option of inflate_init() does not work).
    (wapmorgan)

(taca)