druntime posix .. nothrow!

[Etienne]

Almost everything in druntime's core.sys.posix is currently ..not.. 
nothrow. This causes (me) to workaround by wrapping it with try/catch 
statements which is completely unnecessary, it would be easier to just 
copy those files in the project folder and change them unless they're 
updated in the git head by some kind of a hero ;)

Wouldn't it be easier if extern(c) implied nothrow? you betcha!