Can't build with clang on Ubuntu

[brson]

Clang doesn't know how to link on Ubuntu (and aparently other Linuxes), erroring with

/usr/bin/ld: cannot find crtbeginS.o: No such file or directory

[eholk]

Hmm.. I'm getting undefined identifier errors using clang on Ubuntu. I'll see if I can fix them...

[brson]

Now it also fails because clang can't find unwind.h

[brson]

I did a successful build with a recent 3.0ish build of clang.