putting the (simple) definition in alltypes.h seems like the best solution here. making sys/ioctl.h implicitly include termios.h is probably excess namespace pollution.
these have been adopted for future issue of POSIX as the outcome of Austin Group issue 1151, and are simply functions performing the roles of the historical ioctls. since struct winsize is being standardized along with them, its definition is moved to the appropriate header. there is some chance this will break source files that expect struct winsize to be defined by sys/ioctl.h without including termios.h. if this happens, further changes will be needed to have sys/ioctl.h expose it too.
commit b60fdf133c033d4ad6b04a8237f253563fae5928 broke the SIOCGSTAMP[NS] ioctl fallbacks introduced in commit 2e554617e5a6a41bf3f6c6306c753cd53abf728c, as well as use of these ioctls, by creating a situation where bits/ioctl.h could be included without __LONG_MAX being visible.