(Qbignum, Qfixnum): New variables.

(Qbignum, Qfixnum): New variables.
(wrong_type_argument, Fchar_or_string_p): Use FIXNUMP instead of
INTEGERP.
(Ftype_of) [HAVE_LIBGMP]: Return `fixnum' for Lisp_Int, `bignum'
for Lisp_Bignum.
(Fintegerp) [HAVE_LIBGMP]: Return t for bignums.
(fixnump, bignump, bitint_arith_driver) [HAVE_LIBGMP]: New functions.
(arith_driver) [HAVE_LIBGMP]: Handle implicit coercion to big ints.
(float_arith_driver) [HAVE_LIBGMP]: Handle coercion of bigints to
floats.
(Fadd1, Fsub1, Flognot) [HAVE_LIBGMP]: Handle bigints.
(syms_of_data): Initialize Qbignum and Qfixnum, defsubr bignump
and fixnump.