llvm-base: Don't declare DbgInfoPrinter pass with LLVM 3.3

Keeps consistency between extra.cpp & extra.h
This should have been included in:
d01855daab68727da55db94d35fa8b620dd485d0
Merge pull request #52 from olajep/fix-extra

llvm-base: Don't declare DbgInfoPrinter pass with LLVM 3.3