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.

the old behavior of exposing nothing except plain ISO C can be
obtained by defining __STRICT_ANSI__ or using a compiler option (such
as -std=c99) that predefines it. the new default featureset is POSIX
with XSI plus _BSD_SOURCE. any explicit feature test macros will
inhibit the default.
installation docs have also been updated to reflect this change.

patch by Isaac Dunham. matched closely (maybe not exact) to glibc's
idea of what _BSD_SOURCE should make visible.

- add the rest of the junk traditionally in sys/param.h
- add prototypes for some nonstandard functions
- add _GNU_SOURCE to their source files so the compiler can check proto