[Ada] Delete bogus use of flag_zero_initialized_in_bss

[Eric Botcazou]

> The Ada front-end seems to think that clearing flag_zero_initialized_in_bss
> means that global variables without an explicit initializer will be
> considered to be uninitialized rather than zero initialized by the rest of
> the compiler.

No, it doesn't, you misunderstood.

> Rather than specifying whether the global will be zero initialized or not,
> it specifies by what method it will be zero initialized: whether by placing
> in the BSS section or by outputting an explicit block of zeros.

Yes, that's precisely why the flag needs to be cleared: uninitialized really 
means uninitialized in Ada so the BSS section isn't guaranteed to be zero-ed 
at startup for a pure Ada program.

-- 
Eric Botcazou