libusb: add parser for interface association descriptor

[aokblast]

Reorder libusb20_config to prevent ABI break

[aokblast]

@kevans Do you think we should show IADs inside usbconfig? If so, what is your opinion about the format? IAD is a structure that cover multiple interfaces into 1 usb function. In that case, all interface should have a new indent and put the IAD on the top of It.

[aokblast]

Implement libusb_get_active_iad

[lwhsu]

lib/libusb/libusb.3

550

562

lib/libusb/libusb.h

80

Let's have this sorting enum member change in another commit, also, it seems that LIBUSB_DT_BOS should be placed after LIBUSB_DT_INTERFACE_ASSOCIATION ?

lib/libusb/libusb10_desc.c

786

This config will not be free()'d in the following early return:

• if (iads == NULL)
• if (niad == 0)
• if (iad == NULL)

839

Maybe calling the parameter iad_arr to match the definition of libusb_get_active_interface_association_descriptors?

Or, even align more with libusb_get_interface_association_descriptors to be called iad_array?

841

Do we need to check desc is not null first?

lib/libusb/libusb20_desc.h

260

From the spec, iFunction seems using UINT8_T?

[aokblast]

Minor fixes

[lwhsu]

in man page and code, there are iad_array and iad_arr, would be nice if this naming can be consistent.

lib/libusb/libusb.3

572

573

lib/libusb/libusb10_desc.c

792

Does this also mean success? If so, should we set iad_arr = NULL to prevent that caller still pass the returned iad_arr to free() ?

lib/libusb/libusb20_desc.h

259

is this bInterfaceProtocol only in LIBUSB20_INTERFACE_DESC but not in LIBUSB20_INTERFACE_ASSOCIATION_DESC?

[aokblast]

Minor fixes

[lwhsu]

lib/libusb/libusb.h

293

It seems that we already have this in line 316?

[aokblast]

Minor fixes