[SCCP] Remove wrong and misleading vector handling code.

This code was already commented out and it made some weird assumptions,
e.g. using isUndefined() as "this value is UndefValue" instead of
"we haven't computed this value is yet". Thanks to Eli Friedman for
pointing out where I was wrong (and where this code was wrong).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@274995 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed