selective linking of floating point support for *printf / *scanf

[Joseph S. Myers]

On Thu, 23 Oct 2014, Thomas Preud'homme wrote:

> Hi all,
> 
> I changed the target hook somehow so that more code run in the backend 
> since depending on the target (avr-libc Vs newlib) two different schemes 
> are used: printf -> iprintf renaming or defining _printf_float as a 
> global symbol. I thus renamed the target hook to match such a usage.
> 
> The proposed patch is attached to this email (otherwise it would be 
> mangled).

I'm not clear if you're proposing such a patch for review, but note:

(a) you mean DEF_EXT_LIB_BUILTIN (since asprintf and vasprintf aren't in 
ISO C);

(b) please don't add new target macros such as 
CUSTOM_STDI_WEAK_SYM_PATTERN and CUSTOM_STDO_WEAK_SYM_PATTERN (if 
something is defined in tm_defines and used in architecture-independent 
code, it's effectively a target macro), find a way to implement these as 
hooks instead.

-- 
Joseph S. Myers
joseph@codesourcery.com