Xi: allocate enough XkbActions for our buttons
button->xkb_acts is supposed to be an array sufficiently large for all our buttons, not just a single XkbActions struct. Allocating insufficient memory here means when we memcpy() later in XkbSetDeviceInfo we write into memory that wasn't ours to begin with, leading to the usual security ooopsiedaisies. CVE-2023-6377, ZDI-CAN-22412, ZDI-CAN-22413 This vulnerability was discovered by: Jan-Niklas Sohn working with Trend Micro Zero Day Initiative (cherry picked from commit 0c1a93d3)