Two new ieee_round_type values were added in f18 beyond the four values
defined in f03 and f08: ieee_away and ieee_other. Contemporary hardware
typically does not have support for these rounding modes, so flang does
not support them. ieee_support_rounding calls for these values return
false. Current generated code handles some attempts to set the rounding
mode to one of these unsupported values by setting the mode to
ieee_nearest. Update the code to explicitly do this in all cases.
0b52aa1bdb
