xxd issue when using Ctrl-C

[gngrossi]

@IgorTodorovskiIBM
Entering xxd at the bash shell prompt without parameters and using Ctrl-C after, results in un-displayable characters.

[IgorTodorovskiIBM]

Thanks, I can reproduce. It's likely related to this change:

 931     {
 932       int fd;
 933       int mode = revert ? O_WRONLY : (O_TRUNC|O_WRONLY);
 934
 935       if (((fd = OPEN(argv[2], mode | BIN_CREAT(revert), 0666)) < 0) ||
 936           (fpo = fdopen(fd, BIN_WRITE(revert))) == NULL)
 937         {
 938           fprintf(stderr, "%s: ", pname);
 939           perror(argv[2]);
 940           return 3;
 941         }
 942       rewind(fpo);
 943     }
 944 #ifdef __MVS__
 945   // Disable auto-conversion on input file descriptors
 946   __disableautocvt(fileno(fp));
 947 #16 

We should probably check if fp is a tty or do the autoconversion disabling here:

 916   if (argc == 1 || (argv[1][0] == '-' && !argv[1][1]))
 917     BIN_ASSIGN(fp = stdin, !revert);
 918   else
 919     {
 920       if ((fp = fopen(argv[1], BIN_READ(!revert))) == NULL)
 921         {
 922           fprintf(stderr,"%s: ", pname);
 923           perror(argv[1]);
 924           return 2;
 925         }
 926     }
 927