Include exitfail.h.

Include exitfail.h.
(TEST_FAILURE): New constant, used for exit status if 'test' fails.
(test-syntax_error): Use it.
(binary_operator): Now takes bool arg specifying whether left operand
is -l ARG, so that caller determines this rather than us.
All uses changed.
(term): Use posixtest to evaluate parenthesized subexpressions.
(unary_operator, one_argument): Remove support for -t without operand.
(one_argument): Take argument from argv[pos].
(one_argument, two_arguments, three_arguments): Advance pos.
All callers changed.
(three_arguments): Look for binary ops before "!".  Then look
for parenthesized one_argument expressions, instead of trusting
expr () to do the right thing.
(posixtest): Now takes number of args.  All callers changed.
Treat "( A B )" like "A B".
(main): Set exit_failure to TEST_FAILURE.  Don't depend on
POSIXLY_CORRECT, as we now conform to POSIX by default.
(main) [!LBRACKET]: Do not recognize "--help" or "--verbose" unless.