[Bug libfortran/93567] G edit descriptor uses E instead of F editing in rounding mode UP

[dominiq at lps dot ens.fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93567

--- Comment #4 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
The patch in comment 3 broke gfortran.dg/round_3.f08.

The following should work

--- ../_clean/libgfortran/io/write_float.def    2020-06-13 03:11:55.000000000
+0200
+++ libgfortran/io/write_float.def      2020-07-21 00:37:24.000000000 +0200
@@ -1004,7 +1004,11 @@ determine_en_precision (st_parameter_dt 
       exp_d = calculate_exp_ ## x (d);\
       r_sc = (1 - r / exp_d);\
       temp = 0.1 * r_sc;\
-      if ((m > 0.0 && ((m < temp) || (r >= (exp_d - m))))\
+      if ((m > 0.0 && ((m < temp) || (r == 0.5 && r >= (exp_d - m))\
+                                 || (r == 1 && !sign_bit && 1 > (exp_d - m))\
+                                 || (r == 1 && sign_bit && 0 >= (exp_d - m))\
+                                 || (r == 0 && !sign_bit && 0 >= (exp_d - m))\
+                                 || (r ==0 && sign_bit && 1 > (exp_d - m))))\
          || ((m == 0.0) && !(compile_options.allow_std\
                              & (GFC_STD_F2003 | GFC_STD_F2008)))\
          ||  d == 0)\