Our latest attempt to use Clang’s __builtin_assume caused a crash
in GNU Emacs that we spent quite some time tracking down as being
caused by the switch to __builtin_assume. It’s not known whether
the crash is due is a Clang bug or a portability bug in GNU Emacs.
For now, play it safe and avoid __builtin_assume.
* lib/verify.h (_GL_HAS_BUILTIN_ASSUME): Remove.
(assume): Simplify by not trying to use Clang’s __builtin_assume.