GCC 4.3.0 exposes a kernel bug

> But Gcc should continue to clear it too, because old Linux exists.

This does not buy you anything except slowing down all your code unnecessarily.  Any user
might use a binary built with some other compiler, like the precompiled commercial MySQL
server, or a game.  Software running through Wine is probably built with Visual Studio.  A JIT
like Mono or Java might generate code that doesn't reset DF.  A developer might be using TCC
for ultra-fast compiles.  There is also LLVM: I don't know, but it might not do the DF clear
either.

See what I mean about other compilers?  Do you wish to have every one of them also clear DF on
every function?