Revert commit 149912 (lattner) and add a testcase that shows the problem (which

is that patterns no longer match for vectors of booleans, because you only get
ConstantDataVector when the vector element type is i8, i16, etc, not when it is
i1).  Original commit message:
Remove some dead code and tidy things up now that vectors use ConstantDataVector
instead of always using ConstantVector.

llvm-svn: 150246