[LV] Statistics numbers for LoopVectorize introduced: a number of analyzed loops & a number of vectorized loops.
Use -stats to see how many loops were analyzed for possible vectorization and how many of them were actually vectorized.
Patch by Zinovy Nis

Differential Revision: http://reviews.llvm.org/D3438



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206956 91177308-0d34-0410-b5e6-96231b3b80d8