* m4/gnulib-cache.m4: Augment with 'gnulib-tool --import stdint'.
* checks/check-them: Record expected exit status.
* checks/get-them: Check exit status.
* src/m4.h (eval_t, unsigned_eval_t): Delete, use POSIX int32_t
instead.
* src/builtin.c: All users changed.
* src/eval.c: Likewise. Also document where we are triggering
undefined or implementation-defined behavior.
(BADOP, NEGATIVE_EXPONENT, INVALID_OPERATOR, eval_lex, evaluate)
(logical_or_term, logical_and_term, logical_not_term, not_term)
(equality_term, unary_term): Port from head to follow POSIX
semantics.
(exp_term): Reject 0**0 as undefined.
* doc/m4.texinfo (History): Mention 1.4.9.
(Format, Incompatibilities): Update to document POSIX compliance.
* NEWS: Document this change.