Default will never be printed for `flag_bool` with `def`=`false`

[ej-uses-git]

I was copying over the library and renaming some things and came acorss the following lines in flag.h:

if (flag->def.as_bool) {
    fprintf(stream, "        Default: %s\n", flag->def.as_bool ? "true" : "false");
}

As you can see, the ternary operator there will always result in "true", since we just checked that it's non-zero in the if above it...

Maybe instead we can just always print the default for booleans?