DragonFlyBSD

While looking at issue I discovered that most of systems (NetBSD and FreeBSD
among others) are using gdtoa for floating point to string and string to
floating point conversions. Actually it's true for DF as well,
lib/libc/stdlib/strtod.c is successor of the gdtoa.

Obvious solution would be to update to latest gdtoa code to get C99 conformant
floating point to string and string to floating point conversion. The fact
that FreeBSD and NetBSD are using it should simplify it at least a little.

Before someone mentions it - no, it's beyond my skills at the moment ;).