c_std/ and throw()

[Benjamin Kosnik]

Sorry it took me so long to get back to this Jakub.

> It won't have any effect for strcpy, as the compiler already knows
> that can't throw (see nothrow_libfn_p).  Adding throw() is only useful
> for C library functions that aren't in the C standard, and thus in
> cfns.gperf.

There are around 208 functions in cfns.gperf. That's a lot of
functions that effectively already have this optimization.

I don't really see any significant binary size reduction in the
library itself with this patch.

-benjamin