SSL: Disable support for SSL 3.0 by default.

Requires recent Pike 7.8 or later.

Blocks the POODLE attack.
Merge branch 'patches/poodle' into 5.5

* patches/poodle:
  SSL: Disable support for SSL 3.0 by default.
SSL: The protocol defaults in Pike and Roxen may differ.

The callback set with set_changed_callback() is only called if
the value differs from or is changed to the default.

Fixes disabling of SSL 3.0 by default on Pike 7.8.
Merge branch 'patches/poodle' into 5.5

* patches/poodle:
  SSL: The protocol defaults in Pike and Roxen may differ.
Version bumped to 5.5.57 by buildsystem.