Add create_sid to session_set_save_handler and SessionHandler

A lot of code already existed to allow a custom create_sid handler, but
lacked a specific implementation.

Therefore I have added a 7th (optional) argument
session_set_save_handler, to allow a user function to be supplied for
session id generation.

If a create_sid function is not supplied, the default function is
called in its absence to preserve backwards compatibility.

Likewise create_sid only added to SessionHandler class, and not the
interface to maintain backwards compatibility. If the result is not
overridden, the default is called.
Tests, fixes and optimisations

* Amended existing tests to cater for new functionality.
* Implemented fixes and optimisations recommended by NikiC
* Added create_sid to the registered interface. This was breaking
tests. It also now breaks BC for people implementing the interface
directly instead of extending the class.
Fix bug #65088 (Generated configure script is malformed on OpenBSD).

We fell foul of a "common urban legend"[0], which resulted in us backslash
escaping double quotes that we didn't need to in acinclude.m4. This worked fine
on most shells, but OpenBSD's ksh implementation really didn't like it.

[0] http://www.gnu.org/savannah-checkouts/gnu/autoconf/manual/autoconf-2.69/html_node/Shell-Substitutions.html
Merge branch 'PHP-5.4' into PHP-5.5

* PHP-5.4:
  Fix bug #65088 (Generated configure script is malformed on OpenBSD).
Adding test to stabelize keys used when converting objects to arrays
Adding test to verify that __sleep can handle parent classes' private members
Merge branch 'PHP-5.4' into PHP-5.5

* PHP-5.4:
  Adding test to verify that __sleep can handle parent classes' private members
  Adding test to stabelize keys used when converting objects to arrays
Implements feature Bug #63472 ability to set SO_BINDTODEVICE on socket.
Merge branch 'PHP-5.4' into PHP-5.5

* PHP-5.4:
  Implements feature Bug #63472 ability to set SO_BINDTODEVICE on socket.

Conflicts:
	ext/sockets/sockets.c
Require second parameter of imagecrop()
Fix bug #62759: Buggy grapheme_substr() on edge case
Merge branch 'PHP-5.4' into PHP-5.5

* PHP-5.4:
  Fix bug #62759: Buggy grapheme_substr() on edge case
fix bug #61860: use USearch for searches, it does the right thing
seems to be working fine for me on 32-bit
Merge branch 'PHP-5.4' into PHP-5.5

* PHP-5.4:
  seems to be working fine for me on 32-bit
small optimization
OPcache must be compatible with LiteSpeed SAPI
Upstream fix from https://bitbucket.org/libgd/gd-libgd/issue/75
Use same logic to load WebP image that other formats
fix imagecreatefromwebp and imagewebp protos