Remove __STDC__ conditionals from installed headers

[Marek Polacek]

On 01/27/2012 06:17 PM, Roland McGrath wrote:
> That said, it looks fine to me.  These changes should have zero effect on
> the code generated, so e.g. a stripped libm.so should be identical before
> and after (modulo build ID).  So perhaps you could verify that's so.

I verified this using gcc 4.6.2 on x86_64-redhat-linux.  Disassembled old and
new libm.so are the same.

	Marek