GLFW_RESIZE_ALL_CURSOR equivalent missing

[falkTX]

While porting some software from glfw to pugl, I noticed this cursor type is missing. glfw docs state about this one:

/*! @brief The omni-directional resize/move cursor shape.
 *
 *  The omni-directional resize cursor/move shape.  This is usually either
 *  a combined horizontal and vertical double-headed arrow or a grabbing hand.
 */
#define GLFW_RESIZE_ALL_CURSOR      0x00036009

More on the glfw documentation, we can see this cursor is fully supported:

 *  Most of these shapes are guaranteed to exist on every supported platform but
 *  a few may not be present.  See the table below for details.
 *
 *  Cursor shape                   | Windows | macOS | X11    | Wayland
 *  ------------------------------ | ------- | ----- | ------ | -------
 *  @ref GLFW_ARROW_CURSOR         | Yes     | Yes   | Yes    | Yes
 *  @ref GLFW_IBEAM_CURSOR         | Yes     | Yes   | Yes    | Yes
 *  @ref GLFW_CROSSHAIR_CURSOR     | Yes     | Yes   | Yes    | Yes
 *  @ref GLFW_POINTING_HAND_CURSOR | Yes     | Yes   | Yes    | Yes
 *  @ref GLFW_RESIZE_EW_CURSOR     | Yes     | Yes   | Yes    | Yes
 *  @ref GLFW_RESIZE_NS_CURSOR     | Yes     | Yes   | Yes    | Yes
 *  @ref GLFW_RESIZE_NWSE_CURSOR   | Yes     | Yes<sup>1</sup> | Maybe<sup>2</sup> | Maybe<sup>2</sup>
 *  @ref GLFW_RESIZE_NESW_CURSOR   | Yes     | Yes<sup>1</sup> | Maybe<sup>2</sup> | Maybe<sup>2</sup>
 *  @ref GLFW_RESIZE_ALL_CURSOR    | Yes     | Yes   | Yes    | Yes
 *  @ref GLFW_NOT_ALLOWED_CURSOR   | Yes     | Yes   | Maybe<sup>2</sup> | Maybe<sup>2</sup>
 *
 *  1) This uses a private system API and may fail in the future.
 *
 *  2) This uses a newer standard that not all cursor themes support.

Seems like this can work on all OSes, without the issues of being private API or sometimes unsupported.

[drobilla]

Added in e554f8c