Linux: show newlines in commands as ? instead of space

Since \n is used internally by htop to split command lines, replace \n
with \r in command lines to not display them as space.

Merging the command string will not work, but newlines in commands
should be rather the exception.

linux/LinuxProcessTable.c

@@ -1172,6 +1172,12 @@ static bool LinuxProcessTable_readCmdlineFile(Process* process, openat_arg_t pro
 
       /* newline used as delimiter - when forming the mergedCommand, newline is
        * converted to space by Process_makeCommandStr */
+      if (argChar == '\n') {
+         /* Set to some other non-printable character */
+         command[i] = '\r';
+         continue;
+      }
+
       if (argChar == '\0') {
          command[i] = '\n';