[Issue 20479] octal integer literals don't work with BetterC mode

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=20479

--- Comment #3 from Heromyth <bitworld at qq.com> ---
It totally does not work now with DMD 2.097.0.

The latest error message:

```
/Library/D/dmd/src/phobos/std/array.d(982,49): Error: `TypeInfo` cannot be used
with -betterC
```

OR

```
/Library/D/dmd/src/phobos/std/conv.d(4858,33): Error: array concatenation of
expression `num ~ " is not an octal literal"` requires the GC which is not
available with -betterC
```

--