gcc49: snapshot 20130825.
llvm 3.4

I added formula for LLVM 3.4.
LLVM 3.4 is now in-progress and I couldn't find snapshot archives like
gcc weekly snapshots. So I decided to use the latest source code from
repositories.

Closes #192.

Signed-off-by: Xiyue Deng <manphiz@gmail.com>