[LV] Make LIT test insensitive to basic block numbering

This patch is part of D28975's breakdown.

induction.ll encodes the specific (and rather arbitrary) numbers given to
predicated basic blocks by the unique naming mechanism, which makes it
sensitive to changes in LV's instruction generation order. This patch replaces
those specific numbers with a numeric pattern.

Differential Revision: https://reviews.llvm.org/D32404

llvm-svn: 301345