Divides a by b and returns the integer
result. The result rounding is defined by the round, which can have the following
values:
GMP_ROUND_ZERO:
The result is truncated towards 0.
GMP_ROUND_PLUSINF:
The result is rounded towards
+infinity.
GMP_ROUND_MINUSINF: The result is rounded
towards -infinity.
This function can also be called as
gmp_div().
See also gmp_div_r(),
gmp_div_qr()